This problem requires some iteration. That's why it's all on you - you're the only one who's around enough to bear with the needed testing. But your technique so far has been ineffective.
Focus on this particular data collection:
- Shoot a clear photo of the service panel, and its label, and the studio lights.
- Do they tend to get notably brighter and dimmer as other loads switch on/off?
- Get a gadget called a "Kill-A-Watt" that measures actual power draw on an appliance, and reports volts, amps, watts and VA. The $20 one will be fine, you need to see the changing numbers "live", so the one that lets you see them after you unplug is not useful. Don't go crazy with this thing.
- Hit a library and browse their section on "electrical how-to books". They're in nonfiction/621.31. Browse a few and find one that has a good vibe. You're there to learn theory.
- You will NOT do any repairs in this apartment. It's illegal, and will make you responsible for ALL the wiring problems, even pre-existing ones (how does the landlord know you didn't cause them?) Do not do it. I don't touch anything in my apartment, so you can control yourself. This spring I fixed a huge problem, simply by gathering data competently, knowing who to tell, and what to tell them.
- Turn all the breakers on and all the light switches off. Plug something (doesn't matter) into every single socket (try both sockets in the double sockets). Are any of them dead? If they are, try turning light switches on. Do they turn on? If so, mark them "switched" with a sticker.
- Find every GFCI receptacle or deadfront in the place. For each one, hit "TEST". Search to see if any other receptacles, lights or devices lose power. Then hit "Reset". Don't bother with GFCI breakers.
EDIT: OK. That thing you shot a picture of is your breaker panel. It's perfectly clear this is a normal and modern breaker panel, nothing wrong with it, you're just not familiar with the tech. Now, I prefer cutesy names like "Thor" and "Hawkeye", but I see your panel already has unique names for each breaker... just change the two KIT-GFI ones to KIT-GFI1 and KIT-GFI2.
Now it's time to map all the outlets in your house.
Very similar to what Sunnyskyguy is proposing, except I want you to also mark the outlets using stickers. Why? You'll see. An outlet is anything that takes electricity, so this includes your dishwasher, switched lights, A/C unit, all of it.
- Turn all your light switches on. Get something small that you can easily plug into any socket without drama (so not those lights that trip the GFCI). I like dollar-store nightlights for this.
- Save your computer files.
- Turn off every breaker in the panel. Every one. Do this in broad daylight - it will get dark!
- Turn on the large "A/C" breaker in lower right. Now go around and check every outlet to see if it has power. If any do turn on, put a sticker on them marked "A/C" then turn it off. If anything besides the A/C turns on, that would be really weird.
- Turn on the "REFRI(gerator)" breaker. Go around and check every outlet to see if anything has power. If something besides the refrigerator turns on, sticker it "REFRI". I'm not too worried about it if that happens.
- Now turn on both A/C and REFRI and leave them on through all of this. That keeps your house cool and food unspoiled.
- Next, turn on "SD-LTS", and check every outlet. Sticker anything that works "SD-LTS". . (except the fridge and A/C of course). Then, turn it off again.
- If you find you just can't work without the light, then you can turn SD-LTS back on, but try to keep it off for the rest of this.
- Do the same thing with each and every circuit. Turn it on, check every outlet, turn it off. Only 3 circuits should be on: A/C, REFRI, and the one you are testing. (and possibly SD-LTS). Note that BED breakers are full-width and GD/DW is a double breaker that throws together. Don't worry about that.
- If you already put a sticker on an outlet, still check it every time.
- When you've done them all, turn them all back on.
Now if all this went right, every outlet will have exactly one sticker. If it has 2 stickers, then fact-check that! Turn everything off again, and test that outlet with only that breaker on, and only the other breaker on. If 2 breakers can turn it on, that is a very important fact, and the electrician needs to be told.
Let's chase the music/stolen power
By law, on a newer installation like this, these breakers must feed only your apartment. However from the "music" you reported earlier, it might be feeding another apartment. Now you know what each circuit breaker does, I want you keep breakers turned off, except when you actually need what's on them. The goal here is to get the neighbor to report a power outage, and have the electrician come and fix it (so it's on their power instead of yours).
This is bad because a) you're paying for it, b) If they overload the power, your breaker trips and that's making it hard to understand your electrical... and c) once they figure out they're getting free power, they'll exploit it at your expense.
If you get a knock on the door and the electrician wants to turn the circuit on, fine, let him troubleshoot. But turn it off that evening (unless you need it).
Glad to hear you don't have any double-fed circuits. That can cause a lot of problems and you can now exclude it for good. This whole exercise is giving us a lot more confidence in the wiring, which doesn't sound so bad.
The A/C requiring 2 circuits is normal, I probably should've warned you of that :) The 120V circuit provides fan and 24V furnace and thermostat controls: the devices that call for A/C. The large 240V circuit runs the A/C compressor proper.
The mismarked circuits you exchanged are amusing. Given their destinations (right next to each other) and locations in the panel, I would expect they are multi-wire branch circuits. I won't discuss those any further because they are a Big Bag of Not Your Problem; the important thing is they appear to be correct, and that reasonably explains the mis-marking, and it's a trivial problem. If a problem were present here, then running microwave or dryer would trip the GFCI instantly, everytime.
All appliances tripping all GFCIs can only mean one of two things: a) all the circuits have wiring problems or defective GFCIs; or b) all the appliances are broken. Both of those are highly improbable. I would take the appliances to a friend's house or your workplace and try them there. If they pass there, I for one don't believe in failed GFCIs, so that suggests some sort of persistent wiring problem in triple failure. That was considered highly improbable until Eastern Airlines Flight 855 nearly did a splash landing because all three oil-pan magnets were installed without the required O-rings... And now airplanes have ETOPS stenciled on them to forbid the same mechanic to work on both engines...
As for your bedroom AFCI trips, we still need to know if this is an overload from too much current, or an arc-fault trip from an appliance arcing. Trip it with the TEST button (it will kill power, obviously) and the LEDs should display as they will for an arc-fault trip. Get a Kill-a-Watt and measure the current draw of each appliance on the circuit, and total up the Amps, and see if the total exceeds the breaker rating. That is how an overload trip will occur.
If it's not an overload trip, look at arc-fault tripping, try feeding appliances from an outlet in the other bedroom and see if the AFCI trips move to the other bedroom. If they do, it's an appliance that you moved. Keep in mind extension cords dull the sensitivity of ACFI detectors, so the problem might go away altogether. An arc fault in an appliance is a bad thing, and will start fires. An arc-fault inside the wall junction boxes will also have this effect, but they just changed your receptacles so that seems highly improbable.
As Sherlock Holmes says, when you eliminate the impossible, whatever remains, however improbable, must be the truth.
SOLUTION: GFCI receptacles tripping
Normally, power is supposed to flow from one prong, through the device to do useful work, then to the other prong. If power leaks out of that loop, it can go a third way - including through you. That's called a ground fault and a GFCI has one job - detect that.
In your latest video, you showed where you plugged a device into a GFCI, and it tripped. Working as intended. When you plug in an appliance and it trips a GFCI, that's a problem that got caught before it killed someone.
Your apartment has at least 3 GFCIs - 2 for kitchen countertops, and 1 for bathrooms. When an appliance trips a GFCI, plug it into every other GFCI in the house. If it trips them all, then the appliance is bad. Into the trash it goes. Seriously. Lots of people get into total denial at this point, but don't bother.
Now, what if the GFCI trips with many devices but only in certain receptacles? That is a bad receptacle. It's likely the metal screws are hitting the side of the metal junction box or the ground wire. The electrician can fix that by wrapping it with electrical tape. Or it's broken.
What if plugging into a normal receptacle trips a GFCI? That is normal, 1 GFCI device can protect many receptacles.
What if GFCI trips are random and intermittent? Trip the GFCI. You know how to map which receptacles are on that GFCI. Unplug everything on those receptacles. One at a time, move them onto a different GFCI circuit and let them live there for a week or two. If the problem moves, it's the device. Remember your kitchen has two GFCIs.
SOLUTION: AFCI breakers
The two bedroom breakers are a special type called a AFCI. Like a GFCI, it trips for certain faults. Unlike a GFCI, it's looking for a totally different fault: arc faults - or specifically, wires arcing either from a loose connection or a short. This starts house fires. It's in bedrooms because it happens a lot in electric blankets.
Because AFCIs are built into circuit breakers, you must look closely to see if the breaker has tripped from an overload, or from an arc-fault. These are different problems. If it tripped from an arc fault, look closely at any devices involved. Try them in the other bedroom and see if the problem moves.
Solution: Plug lamps into those switched outlets
You identified some light switches that switch receptacles. That is a normal, modern construction technique, and it's done because it's cheaper than wiring ceiling lights. You are supposed to plug a desk or floor lamp into that receptacle.
In fact, the building code requires switches in the usual/expected locations.
Once you do that, those "useless switches" will make sense.
I know you don't need it, but it's not for you. It's for guests, meaning First Responders. So the fireman can "clear the room", the EMT can work, or the cop can see you're holding a computer mouse and not a gun.