Different methods are taught and acceptable, and most of the times there is more than one way to do it right. Presenting a solution might even be misleading, and it will be obvious whether you [...]
It is shown in the tutorial: While adjusting the CDI or heading bug, + and – are displayed on the top left and ride side of the instrument. Tap there to adjust in increments of 1°.
You do not have to try to turn, but after tapping swipe left or right. You can use the whole screen, there is no need to stay close to the selector after tapping it.