Courtesy of Color Grading Central
Final Cut Pro – One More Way to Adjust Levels
Just in case you were wondering…
You can also adjust audio levels directly in the Timeline. To turn on Timeline audio levels, click the small black mountain range in the lower-left corner (Apple calls this the Clip Overlay button).
This displays red rubber bands all over your audio clips. Drag the rubber bands up or down to set levels for each clip.
This is the audio level setting technique that I use the most.
Note: You can use the Pen tool (press P) to set keyframes for these audio levels.
Courtesy of Larry Jordan