Why does powerpoint go to different page when I don't touch my mac?
At the school where I work, those who have the oddest problems sometimes can't remember when they last restarted their MacBooks; have many apps open perpetually with some apps having many documents open within, etc. Purists scoff at the need to restart macOS, but I think it is the first, best step to resolving odd behavior.

In addition, if you do use a BT device at your desk, (or where you do most of your work,) and leave it behind, disable BT when you are presenting elsewhere.