Follow this official document on how to do the calibration process…
The only problem here in this document is that it only stops at Detent no. 4, as shown in Step VII. You should continue to do the same thing for Detent 5, and press the two red buttons again before contiuing to step VIII and onwards.
If you have the spoilers and flaps addons attached. Make sure you move them along with the throttle before pressing the red buttons at each detents.