Sounds like you're accidentally selecting the board graphic when you move, though this is likely to be due to the behaviour of the browser, as I'm sure you'd notice if you were doing it yourself. 99.9% sure this is not a configurable option, more an oddity of browser highlighting. The highlighted board would appear very much as you describe.
I have noticed that different browsers on different operating systems behave differently viewing chess.com games. If it's really annoying, I'd suggest trying a different browser to see if it persists. If it does, then it's a mystery to me.
When I move the board lights up and is blinding. Sometimes the browns blend together. Is there a way to turn this awful function off?
Thanks.
Glenn