I hope you hadn't purchased any media or apps with the old ID. You won't be able to redownload anything. Items cannot be moved between IDs and a second ID is not something most people want to have.
Change iTunes Store account on an iOS device - Log out of your current account with Settings.app > Store (Settings > iTunes & App Stores on iOS 6) > tap on your AppleID. Log in with a different account. Note, turning on automatic downloads or re-download past purchases may tie the device to that account for 90 days - http://support.apple.com/kb/HT4627
https://discussions.apple.com/message/18484935 - "In order to change your Apple ID or password for your iCloud account on your iOS device, you need to delete the account from your iOS device first, then add it back using your updated details. (Settings > iCloud, scroll down and hit "Delete Account")
Thank you very much for trying to help me.
My ipod touch details won't stay long enough on my screen for me to action anything as a box pops up, asking for my password for the old account.
I can't delete the account or re-set it or anything.
I don't understand why it hasn't behaved like my ipad and iphone that are now both associated with my new apple ID.
I only use the ipod for playing music form my itunes