You can control, balance, and adjust the volume an added music dips to when a video or voiceover comes on, from the music Volume
panel.
By default, music is at 0.0 dB (it's original volume), but the Ducked volume
option can be activated to have the volume of our music duck to a certain set percentage when another video or voiceover is playing, allowing us to balance the music volume when a video or voiceover plays on top.