How do i change settings on iTunes or iPod?

i am trying to make my iPod play the same thing in both headphones. Most songs play different sounds and or instruments. My iPod no longer plays the left headphone and i have tried other headphones and still nothing. It is the iPod itself. The headphones port.How do i change settings on iTunes or iPod?
Well, the settings in the ';Settings'; app on your iPod has the option of changing the sound it produces. I think i have mine on EB, Classic which is like the first one on my list. None of my songs play different things with the different headphones, so maybe thats your problem.