The birthday on the settings aren’t saving even though I’m clicking update profile

If you searched for this problem here you would find many others before you with the same problem. The answer now, as it always has been, is to set your age, then log out (possibly close browser too) then log back in.

try to update it by putting your data then save it. after that try to re log in so your data get saved. some time it occur due to the cache.