It's not going to be a setting, that flicker, and the way the screen is jumping, would point to a more serious problem. No idea what's doing it. It might just be caps, but that's a shotgun approach to a specific problem.
People love these sets, and there is lots of info out there. I had this bookmarked -
https://archivedforum.beoworld.org/forums/t/24571.aspxafter that, I would keep googling info on the set and the problem in different words, over and over again.