Ducking in iMovie 10 iMovie 10 makes ducking a lot less easy... I'm trying to make interview clips automatically reduce the music, but it's making life difficult for me. Can someone please tell me how to do audio ducking in iMovie 10? Thank you!
The audio ducking controls in iMovie 10 are in the adjustments bar under the sound tab. In the sound tab, there's a slider labeled "Lower volume of other clips" and this slider ranges from around 20% ducking to 100%.

More about this in this tutorial video I made: https://www.youtube.com/watch?v=EChiImCZbno