Rebinding Aircraft/Helicopter Yaw to mouse movement does not work.

I am trying to rebind the keyboard and mouse aircraft controls from pitch/roll on mouse and yaw on A/D to pitch/yaw on mouse and roll on A/D as that feels a lot better to me.

But rebinding yaw to sideways mouse movement seems to do nothing.

P.S. it would be great to have a vehicle testing range so I didn't have to get in game and fight my teammates to get in a plane/heli just to see if my controls are set up right - then crash immediately when they aren't.