C1 & C2 Buttons with goggles on?

[Lee Snook]

As I understand, when the goggles are on, the C1 and C2 buttons are now the "Fn" and "Back" buttons on the goggles.
1) But, when I press the "Back" button, nothing happens and the exposure doesn't change.
2) Pressing the Fn (center focus) button brings up the crosshairs on the screen who's center position is controlled by my head movement. What do I press next to refocus using the crosshairs?

 

[RyanW]

Thanks Lee, been asking myself the same question the past few weeks. Ups anyone ?