Can’t use Xbox on my monitor after bringing it to a buddies and altering to 120hz from 60hz

Went to a pal’s dwelling to play D4 over the weekend. We had been having issues on his television having or not it’s locked to 480-620 with the sport solely taking on a fraction of the display screen. We needed to go in settings and go to the video constancy and overscan space to repair it. The issue now’s that now that I’m dwelling, my monitor doesn’t assist 120hz and I don’t know the best way to change it again. Any assist could be appreciated.