I'm a BJJ whitebelt and during one rolling session I was attempting to put the guy in an armbar from sidemount. I had his arm, but it wasn't fully extended because he was grabbing onto his other hand. Now this guy had a really strong grip, and I tried to break it, but moved to mount because I didn't want to go apeshit trying to rip his arm off (it was just training after all). However, what should I have done instead? I know there are some things you can do to loosen the guy's grip (I just forgot what they were). In general though, should I work on putting all my effort into the sub, or move to a better position instead?