That switch it's used to select what indication you'll see on the *analog* fuel indicator which is just above it.
Ah, yes, sorry, I did figure that out, but failed to state it in the 1st post of this thread.
Perhaps I should ask if fuel can be transferred from one tank to another? Or if a tank can be selected or if all tanks drain equally whether by engine burn or dump?
So far, I'll test, although is this has been covered elsewhere?