What I have is that when I turn on the kitchen faucet to warm while washing dishes and someone uses the toilet or cold water on another faucet then the kitchen faucet gets very hot. I am on city water and pressure is at 90 and 3/4 mains. Thank you
It sounds like you have an unequal (probably low) pressure hot water system, which is common in older homes.
Some taps have a "venturi" system which helps with this by using cold water flow to suck water from the water tank. Alternatively limiting the flow of the cold water (probably not what you want) or adding a booster pump to the hot water will help. I imagine the "gold standard" solution though would be to convert to an equal pressure system.