Some of my MP3's are different volumes than others, can I make them all one volume level somehow??

Answer 1

You cant, its the content of the recording. Whoever made the mp3 just did a poor job recording it. Its not your fault with it, its the file itself.

Just go to volume control and play with the playback when you get a bad mp3 quality file.

You might want to try out http://www.winamp.com since it has a bunch of automatic controls that you can be manually adjusted to fit the way you want your music to play on your computer.

Answer 2

yes, if you are using iTunes, there is an option which help to automatically adjust the volume to a constant level.