Is there a way to adjust the volume on all clips so they all have the same volume?

I'm making a highlight film of my two children, and wonder if there is a way to make all clips have the same volume. I know I can adjust the individual clips decibel niveau, but ven though I adjust them to the same level i.e -6 decibel, the clips volume are not the same. Any suggestion, or do I have to adjust each clip with different decibels niveaus and try to make the volume the same, like one clip can have -6 decibel, one light have 3 decibel and so on in order for the volume to be Aamodt the same.