Click the Play music button to preview the music.
Drag the Volume slider or type a number to make the music louder or quieter.
To play the music repeatedly, turn on the Loop Playback option.
Click the scissor icon to trim, and adjust the music duration by dragging sliders on each end of the music track to fit your video length.
Move the slider of the Fade In & Fade Out option to make your music match the video better.