how do i switch itunes store account on my ipod

You can log out of your currently logged in account by tapping on the id in Settings > Store (Settings > iTunes & App Stores on iOS 6) and you can then log in with a different account - but if you turn on automatic downloads or re-download past purchases then you risk tying the iPod to that account for 90 days : http://support.apple.com/kb/HT4627

Yes - is it an iPod Touch ? If it is then you should have a Settings 'app' on it