# How to rotate a set of control points while masking

I'm making another lightsaber fight. It involves quite a bit of masking. A lot of times, when I'm masking around an arm for example, the arm will somewhat rotate in the next frame. How come I can't press A to select all the control points, and then R to rotate them around their midpoint? I can use G to translate, however, I cannot use S to scale (R and S only adjust the control points individually). How can I change this? Thanks.