Apparently there is a shortcut for the gimbal roll adjustment.
This is useful during mid flight.
1. Hold down C2(right side button on the back of the R/C)
2. Adjust the wheel left or right to adjust gimbal (right side)
This information was derived from another member on DJi's forum.
I was manually setting the gimbal roll adjustment while flying using the + and - buttons. I'd get the horizon level looking and a second or so later the horizon would pop out of alignment again. My manual adjustment wouldn't stick. This happened over and over.
Is this newbie operator error or...