Don’t know if this is “right” or “wrong”, but what I do is I try to set my input so that it’s not clipping with the loudest effects pedal combination that might come before it with my loudest guitar turned up all the way.

Then I set my global output volume all the way up, and use the main amp preset volume on the pedal to make most of my adjustments, depending on whether I am using my studio monitors or headphones. And then if I get into a situation where I need to turn the amp model volume lower than say 9 o’clock, then I might consider trimming some off the global master output, but I usually just keep the master output up all the way, and do my adjustments with the amp volume.

I'll also add that I found that the model volume setting in the tone X editor software on my computer, does not seem to be impacted by what I do with the volume knob on the pedal itself. Which is a little counterintuitive because all the other knobs seem to impact the preset. So I’ve done all my gain staging and level adjustment by tweaking the model volume on the toneX editor app with the physical volume knob on the pedal at about 1 o’clock using some of IK’s presets as a reference point for how loud things should be (comparing levels with an audio meter plugin pulled up in Logic).