You can set different levels of volume for each scene.
Please note that music will auto fade in the last second of your final generated video.
In the second step of the Editor (after you click Continue), click on SCENE in the left tab.
Now scroll down and click on VOLUME.
Use the slider to increase/decrease the volume.
The Video slider represents the volume of the video clip in the scene. The Background slider represents the volume of the music track that runs in the background.
The Narration slider represents the volume of your voiceover.
To remove the music, select No Music in the Music tab