You can use VCA channel strips to control the volume, or automate a submix, of tracks that are assigned to the VCA group.
Do one of the following:
Choose Options > Create New VCA Fader from the Mixer menu bar.
Select one or more channel strips, then choose Options > Create New VCA for Selected Channel Strips from the Mixer menu bar.
Click the channel strip’s VCA slot, then choose a VCA fader from the pop-up menu.
Click the channel strip’s VCA slot, then choose No VCA from the pop-up menu.