The fact that they sometimes seem to not stay clicked is a known bug. Some switches won't update after you've clicked them until you move the mouse away.
The manual's currently undergoing renovations and this is now included:
The MIDI screen displays options to enable and disable MIDI feedback.
Sends MIDI from the MIDI-in DIN jack directly to the MIDI-out DIN jack.
Sends MIDI from MIDI controllers plugged into the USB-A ports back to those very same MIDI controllers.Show More...
Sends MIDI from a USB host plugged into the USB-B port back to the very same USB host.
Exactly what would midi feedback be useful for?