resetting volume level in itunes

I'm not sure, but it might be that after adjusting your slider, the software redefines the new volume as Zero. If you increase volume 2 x in a row, does it get much louder?

The reason for the volume adjusting back to the center is because of a 'default' setting or something like that when you add new music to your ipod library(or your itunes library).
I adjust the information settings for my entire ipod music library occasionally. If I DO NOT add new songs, podcast, tv shows, etc., the volume (and other settings) stay to where I had orginally adjusted them (i.e.- volume pulled to 100%). When I add a new song with a different volume preset, the next time I open the information (apple-i) for my entire library, the volume automatically is at the center control b/c the information panel cannot show the volume discrepancy between the new song and the rest of my stuff at the same time. It's a little annoying, but it reminds me that I will adjust my volume again.

You can always put the volume back to the ZERO, make sure the little blue box is checked, & reset all your music to that one level. Your ipod and itunes should have a SOUND CHECK during playback to automatically adjust your volume, too...