How to keep my different video's audio levels the same?

I make minecraft youtube videos and have felt like i'm just guessing with the audio levels from video to video. I feel like my latest video's levels may be too high, but you be the judge please… _x0 I use Sony Vegas to edit and I usually just make sure the levels aren't going in the red, and that's it. Is there an easy way to make sure all my audio levels between videos are the same?

Download SoundEditPlus. C:

Hope, this helped. If not, please contact me for more help.

P.s, You have nice videos.

Without downloading any plugins you just have to guess your volume bar or remember the decimal besides the audio bar.
You could also try lowering down your mic volume if thats the case.