Persistent Issue with Xbox Controller Button Mapping in Games (RB + RT)

Hi there, I'm experiencing an issue with my Xbox controller. Whenever I enter a game, the functions of the RT and RB buttons seem to change. I can temporarily fix this by going into the settings, selecting 'Custom Controls', and then switching back to 'Classic'. This restores normal functionality, but the problem has been persisting for about two weeks now, and I can't seem to find a permanent fix. Could you please help me with this? Thanks