is this only happens when you watch the video or play the games?
because im using swipe gestures as the navigation bar option, so i don't experience this kind of issue.
try to clear the cache of your settings and reselect the button navigation option, and see. if the issue still persists, you might have to reset your device.
as another alternative, you can reach samsung careline at
1800228899
and request them to control over your device remotely (they won't breach your privacy!) to solve the issue.
