Normally that would be active. By activating that and setting it to tail channel you can adjust the tail gain live. You could probably set any of the gains to that and adjust them as you fly. You can do only one channel at a time that way.
Been busy on my ski motors. These 230s look just fine on the SHELF! This 270CFX so a rockstar. I need to just send this heli to someone to tune. Any takers? My season (jet ski) is upon me and the helicopters will get shelved if they are a pain. If it flies and has current PM I will cycle a battery when available.