Gears keep auto dropping esp in hills
changed the chain a few times


Have you also changed any of the corresponding drive-train ie. cassette and / or chainrings?

Check the wear on your cassette. If the teeth are thinned-out the cassette is also worn and you will need to replace this also.
Check the chain-rings - if these resemble shark-fins these are also worn out.

Unfortunately drive train wears together and replacing one part of them often creates a skipping gear where the chain no longer sits comfortably on the drive train due to previous wear.