Simply follow these instructions:
1.) Open your video in edit mode. Click on the sound you wish to alter. This sidebar will pop up. Roll your cursor over "Volume". Another sidebar will appear. Here you can quickly choose preselected volume levels that will apply to your whole sound.
2.) You can also choose "Advanced Settings" at the bottom. This will take you to a new modification tool.
3.) Here is a breakdown of what each tool does. You can choose to fade your sound at the beginning and/or end. You can alter the duration of the fading. In addition, you can choose the "Constant Level". This will control the entire sound level. For example, if you do not want the pre-adjusted option of 25%, you can choose 20% or 17%. Click the preview button to hear the track. Press save and be on your way!
Look at you! Well on your way in creating beautifully collaborated sounds to play throughout your video. Learn how to trim your audio clips Here. Happy animating!