drill through the control surface and use screws through the plastic backing plate that comes with the horn. don't over tighten...tighten until the backing plate and control horn are snug and touching the control surface. then 1/4 to 1/2 more of a turn...I will then,one at a time, loosen the screw and use a drop of gel super glue on the screw threads. for torque lock
Never glue the horn to the control surface.