Apple Final Cut Pro 7 - Manual (Page 886)

When you first open the Audio Mixer, the default view is View 1, showing all audio tracks
in your sequence. Any tracks you show or hide using the Track Visibility controls while
View 1 is selected are remembered as View 1.
View 1 showing only
the first four audio
track strips
If you click the View 2 button and then show or hide audio track strips, that altered layout
is remembered as View 2.
View 2 showing only
the last three audio
track strips
Clicking the View 1 button restores the state of the Audio Mixer to View 1, the way it was
before you clicked the View 2 button.
886 Chapter 55 Overview of the Audio Mixer