Note that I have the non-pro version, but I think this still applies.
That button can't be programmed at all. That is called the "clutch" button and is used for switching profiles without using the profile manager. Push it and the LED on the lower hat on the stick begins blinking. When this happens, you can use that hat to cycle up/down through the profiles. Left clears the profile and right selects the one currently displayed in the list.
Don't worry, I have the paper version!:bash: And I have two copies of the FAR/AIM, and the Private Pilot Manual, and......
Well, you get the picture:pilotfly:
Being and aerospace engineering student helps too.
Just a clarification: the AoA displayed in the cockpit has nothing to do with the horizontal stab. As Pyroflash said, the AoA is the angle between relative wind and the longitudinal axis.