C1 + left wheel changes pitch of fpv cam
Left wheel changes pitch of payload cam
In Free mode, left wheel + C2 pans/yaws the payload cam
In follow mode, it simply changes pitch.
You should be able to change between free-follow by giving a long press of the C2 button... but it also has a third mode which is Reset (recentres yaw of payload cam, but not pitch).
I've found the long C2 press to change modes a bit unpredictable as to how well it works - best way to check which mode the gimbal is in is to look at the green icon on the left of the DJI go screen. You can also use that same icon to toggle the different modes.
From memory, the Pattern is follow->free->reset->follow... repeat.
Hth