Expression / Volume pedal on channel strips

You can assign the volume/expression pedal at the concert, set, or patch level .... depending if you want it doing the same thing at concert level, or to change its function for different patches.

1) learn the pedal in the layout window, so your layout control is visually changing and responding as you move the pedal.

2) in Edit mode, select the patch you want to fix up (concert level, set, or patch .... whichever you want).
3) select the channel strip you want to control.
4) select the volume control you assigned in step 1 on the screen. make sure you can view the inspector(s).
5) in Screen Control Inspector, go to Unmapped, and drill down to the attribute you want to control. If you already have the control mapped, you will need to unmap it first.

Another thing I have found useful is to give the volume pedal a 'neutral' MIDI number e.g. 17 instead of MIDI 07 (volume). It is very easy for any pedal numbered as 7 or 11 (expression) in MainStage to start changing sounds that they shouldn't.

After that, Learn the pedal in Layout & Assign in Edit in the way that ddd outlines.