Sometimes my kids will be playing on my phone and when I get it back, weird settings have changed, and I have to do internet sleuthing to figure out how to return my phone to normal.
This is one of those examples...one day after getting my phone back I noticed an annoying color inversion tab floating around the edge of my screen. After some digging I figured out how to get rid of it...hope this helps if you find yourself in the same boat.