After the new firmware update (1.5) I was trying to use the "C2" button under the right side of the controller (along with the wheel/button) to adjust gimbal roll or horizon tilt. It worked before the new firmware, but I can't seem to find it with 1.5FW...any ideas if I'm missing something??
The "C" buttons are programmable. Look in the General Settings (icon at the upper right corner of the Flight Screen) screens. I think it is the controller icon that has the option. Let us know how it goes.