daewoo ace h50s - fanuc 16-m tool offset page

Have a new to me 1997 daewoo and trying to set tool offset on Daewoo. When I go to offset page I get a ‘data’ column to input info about tool, guessing this is tool length? I hit soft key and doesn’t change the screen. I know there is A, B, and C offset pages and looks like mine is set as A. How do I change to B? Googling a bit it looks like C is an option with Fanuc but B should be there somewhere?? I've tried changing some parameters on line 5001 but that didn't change anything..