How can I see what firmware versions I have installed at the moment?

For the B1:

1. Switch off the unit.
2. Press and hold the ENERGY/SETTINGS dial and then press and hold the TEST button until the B1 switches on.
3. The current firmware version is now shown in the Display.

 
For the B2:

1. Press both model light buttons while turning on the generator
2. The current firmware version is shown on the display.

For the Air Remote TTL-C, Air Remote TTL-N, and Air Remote TTL-S:

1. Press and hold the MODE button (upper right) for 10 seconds when the remote is turned on.
2. When “Hello” is shown in the display, release finger from button.
3. The current firmware version is now shown.