Perpendicular Sitting

We're doing well with class homework: fast sits, stand and stay while I walk around her, turning left or right, heel, and jump sits (still need to work a bit on this). But Bella normally sits perpendicular to me versus parallel. My fault. I haven't insisted on it until now. Moving her bottom to a parallel position confuses her, so I'm not quite sure how to proceed. I do give lavish praise when she manages a parallel sit, so perhaps this will be the clue. To be honest, I don't really care how she sits as long as she does sit, but it may not cut it in the classroom!