Does anybody know how to set the trim (aileron and rudder)?

I have considerable problems having the aircraft flying "straight and level." Any flight changes to the trim cause an immediate, almost uncontrolable spiral that usually ends in a crash.

I have reviewed the Flight_model.cfg in the   ...\Official\OneStore\asobo-aircraft-generic-turbo-singleengine and cannot see what could be corrected.

Is there a known solution? Where should I look?

What aircraft are you flying?  

Are you using the autopilot when you observe the 'spiral'?

Are you sure you have your controller calibrated, noise free, and with a sufficient deadzone to avoid any spurious inputs?

It is best to use an axis on your joystick or yoke for trimming so you can reduce the sensitivity of it's movement.