How to fade Music?
These steps will show you how to fade the Music track on your Video.
Step 1: Click on the Advanced Editor option on the top left, beside Storyboard (This is if you are on the Text-to-Video workflow. If you are on the Pre-made Templates or Blank Template option, you may skip this and go to the next step)
Step 2: Click on the Music track.
Step 3: Click on the Fade option on the right. you will get a dropdown giving 2 options. The In value indicates how many seconds from when the Music starts will it begin to "Fade In". The Out value indicates how many seconds before when the Music starts will it begin to "Fade Out". Use the ^(Up) arrow keys to set a Value from 1 to 5, and the Down arrow to reduce it (5 seconds is the maximum value, any more and there won't be any fade effect).
Side note: If you trying to have the Music fade out with the end of your Video and adding a Fade - Out value, make sure to drag and line up the end of the Music track with the end of the last scene.
Hover over the white vertical marker, available on either side of the track. Once you get the horizontal resize icon, click and drag either end, to increase or decrease the length of the track, and line it up with the end.