How do i make my brush rotate?

Ok, so I'm trying to get my acrylic brush to act kind of like a real brush.

I'm using acrylic  Real  Dry  Flat

The brush indicator shows a vertical oval.  For the life of me, I can't figure out how to turn it!  what if i want to make a downward stroke?

The entire angle panel is grayed out.  i can't change anything there.  Where do i go to adjust this thing?

turning the page does nothing, it still draws the same direction.

I'm using a cintiq companion 2 BTW.