I have a shower drain cover which is loose.  I don't have any leaks, but the plastic grate that covers the drain hole is loose and slides around.  What kind of glue should I use to keep this plastic in place without making it too permanent?

Here is the bottom of the cover and the hole I wish it would stay in for a long while:

[![drain hole and cover upside down][1]][1]


  [1]: https://i.sstatic.net/KhBAJ.jpg