Most clips should have volume faded in and out. Controls for fade ins and fade outs always appear in the upper-left and upper-right corners of clips.
In the upper-left or upper-right corner of the clip, drag the fade icon inward
Drag further in for a longer fade, or a short distance for a short fade
Drag up or down to adjust the fade curve.
Crossfading allows you to overlap clips and for the sound to blend seamlessly (one clip fades out while one clip fades in). When you crossfade clips on the same track, you overlap them to determine the size of the transition region (the larger the overlapping area, the longer the transition).
Place two clips on the same track, and move them so they overlap.
At the top of the overlapping area, drag the left or right fade icon up or down to adjust the fade curves.
Every clip has a yellow line, which indicates the volume of the clip. Click the yellow line and drag it up or down to easily adjust the volume of the clip. Double-click on the line itself to adjust volume up or down in a specific spot.
If multitrack clips have very different volume, making mixing difficult, you can match their volumes. Because the Multitrack Editor is nondestructive, this adjustment is completely reversible.
Using the Move or Time Selection tool, Ctrl-click (Windows) or Command-click (Mac OS) to select multiple clips.
Choose Clip > Match Clip Volume.
From the pop-up menu, choose Loudness
Enter 10 dB as the target volume