Throttle percentage

Hello everyone,
I have a hexacopter flying very well and I enjoy it. The only problem that i have right now is the chanel 3 percentage displayed on the HUD. It doesn’t go more the 20% , hover at 16/17% but i never see the percentage go over 25. From the log I see that the copter hover between 0.3 and 0.4.
How i can adjust those values?

Thank you

Nobody know how to do it?