They used to be switched on by pressing the Shift key and pressing the large encoder knob. But that seems to have changed now. Just press the Tracks button to bring the meters on/off.

Yes you are right in that they won't default to being on. But it only takes one press of the Tracks button to bring them on though.

I would not be using these meters for anything accurate though. They are more of an indication that a signal is present. Also they are peak reading I think. So low rms levels wont even show anything on them either. There is a way apparently getting them to show rms levels but that might require a SYSEX being sent to the Faderport.