you assign a switch to the x1/ch6, set it to it's lowest setting wich you'll see show up after assigning and writing to the naza, when you move ch6, you'll see the gains go back and forth, mine was going 100-400 when first set then type in the lowest number you want with the switch at its lowest setting. mine is set to 120 at the lowest setting, 190 to the highest setting. you have to make that gap it does adjusted with the endpoints of the switch your using. think my endpoints are like 25% and -25% to get that gap. After changing the endpoint you have to retype the lowest number you want with the switch at it's lowest setting again. It's a little tricky to figure out the first time, but you get used to dealing with it. Right now mine are on ail,ele......... yaw and altitude on mine are fine
if it's not a sliding or rotary knob, use sub trim to set your middle number after setting the lowest with switch at it's lowest