Well since you're asking cops are in a position of authority. If they tell you not to move, then don't move. If you reach for your waistband while they have guns drawn and pointing at you then you're gonna have a bad time.

There are definitely cases when there are multiple officers shouting different instructions at you. If I was in a situation like this I would keep my hands up and slowly get on the ground face down with my hands on my head and hope I'm not shot at....it's pretty sad when it comes to that