Background Music

I am trying to edit a YouTube video. The only thing I have to do is insert my commentary and background music. I insert it all and everything should be 100% done. However when I listen back, the background music gets REALLY loud when my voice gets lower or if I stop to take a breathe. I can put the music at the lowest possible volume but it is still way too loud if I'm not talking. As you could imagine watching a YouTube video in which the music's volume was randomly changing would be annoying. Is there any way to change this? I want the background music to remain the same volume at all times whether I'm talking or not. Thanks