How to change FBW-B but keep Auto speed

I fly Arduplane with no air speed sensor and hand launch in FBWB mode then which to “Auto” mode. I change the settings in “Trim_Throttle” but it controls FBWB, Auto, and other modes setting. I would like to just change FBWB to a higher setting if possible. What are my options?? Any help will be very much appreciated.