Yes like Chris said, do it from your radio. You have exponential and dual-rates setting that will help you to lower down sensitivity of your stick movement.
Which radio you have?
the yaw stick is easily affected when constantly changing throttle, causing unwanted yaw,
this would be great to know how to do it on the 9X transmitter
I think you're experiencing a side effect of sudden throttle changes, it's not an input issue.
I don't have my 9x here but it was fairly simple - in your model menu, you need to define a new curve (it has pictures :-)) and assign it to the output channel - try with mission planner first because you can also reverse the movement accidentaly.
There is also EXPO in the channels menu, but I have not used it because I wanted something between expo and deadzone.
You should get to know 9x if you use it regularly, some functions are invaluable.
I use 10% (+) EXPO with my ALE & ELEV to lower the touchyness. If I use more than 12% EXPO my quad lags to much and is slow to respond making it hard to control. You can use this for the rudder as well. I personaly like a very fast acting rudder.
(+) EXPO slows the sticks down
(-) EXPO speeds the sticks up
I want to increase stick sensitivity instead, is there a way to do that?
Also, the dead gap in the middle of the stick range is too large for our taste. I have found the defaults in radio.pde, but is there some sort of parameter that can be changed instead so we don't have to recoompile?
yes, add negitive expo instead of positive expo at the transmitter
Yeah that is of course a way to reduce the apparent width of the dead gaps. But what I really wanted was more control authority..