How to assign 3D stabilisation switch to Frsky tandem x20s

[zozo]

Hello,

I have set up aura5 lite into a plane and it's working great on the FrSky Tandem x20s however the only thing is not working is the assignment of the switch with which I can select the 3D stabilisation type. Anyone knows how to do that?

 

[Gizmo6]

https://www.flitetest.com/ftaura5 time stamp about 7 min covers assignment of a 3 position switch

good video using the X20 and Archer Rx but process of switch assignment is much the same