When the number of channel strips in the Mixer exceeds the amount of available space, you can change the Mixer view.
You can use the Single, Tracks, or All button to display only those channel strips that you need for the task at hand, or filter channel strips by type, using the channel strip filter buttons. You also have the option of working with narrow channel strips or hiding the legend that appears on the left side of the Mixer.
Do either of the following:
Click the Narrow Channel Strips button to reduce the width of channel strips.
Click the Wide Channel Strips button to increase the width of channel strips.
Choose View > Hide Legend from the Mixer menu bar.
Choose View > Show Legend to show it again.