How to change the audio output for the Metronome

Hi

I want to route the Metronome (and vocal cues) to in-ear monitors for live performance.

I understand I can do this in MainStage by using different outputs for the above tracks vs the rest of the 'Concert'.

I tried to follow the Manual instructions :

Change the audio output for the metronome sound

1. Choose MainStage > Preferences > General.
2. In the Metronome section of the General tab, choose a different audio output from the Output pop-up menu.

PROBLEM

1. In the General tab only outputs 1-2 are available/selectable (Presumably these are also default for the entire 'Concert')

2. Why is this process in the Manual if it is not executable (without doing something else/additional set-up) ?

3. This is probably among the most critical yet most basic set-up requirements for using MainStage with a live band, so why am I having to ask for help at all !

Rant over (its been a long day)

Grateful for any help in resolving this. I'm assuming I can route both the Metronome (as a click track) and vocal cues to the same outputs, which are separate from the rest of the Concert...or should I change the outputs on the other tracks and keep outputs 1-2 for the metronome/vocal cues ?

Thanks in advance for any advice and apologies for my frustration. JM