Q: I’m trying to update some apps on my iPod touch and it asks for my password but the e-mail address it shows is one I haven’t used in over a year and the password that I used to use won’t work. I used a new e-mail address and password when I set this up and that works fine to get new apps. I’ve checked “My Account” on iTunes and it only shows the new, correct e-mail address. How do I get my iPod touch to get rid of the obsolete e-mail? That old e-mail is now invalid and I cannot access it.
– Jerry

A: The likely problem is that at least some of the content on your iPod touch was purchased with the old iTunes Store account.
If it is iTunes that is asking for the password, then the likely issue is that you have applications or other DRM-protected content such as video or older music tracks from the pre-iTunes Plus era that you are trying to transfer onto your iPod touch. If the iPod touch itself is what is prompting your for the password, then the likely cause is that some of the applications that you are trying to update were purchased with the old account.
Unfortunately, there is no easy way around this except to either recover your password for the old account or to re-download the applications in question under your new account. If these were free applications, then this should be a relatively simple matter to fix—just delete the original apps and download them again using your new account. If they were paid apps, then you would need to buy them again under the new account, in which case you may be better off trying to recover your password.
You can determine which account was used to purchase an application by going into iTunes, selecting the application from the “Apps” section in the source listing and choosing File, Get Info from the iTunes menu.
The “Summary” page in the file info dialog box will indicate the iTunes Store account that was used to purchase the app.
Further, since you haven’t used the account in some time, it may help to sort the Apps listing in iTunes by the purchase date so you can easily see which apps in your library are the oldest. This can be done by choosing View, As List from the iTunes menu to see your apps in a simple list view and then adding the “Purchase Date” column by selecting View, View Options and then clicking on that heading to sort the list by Purchase Date. Keep in mind, however, that the “Purchase Date” column will show the date of the last update that was downloaded, not necessarily the date when the application was originally purchased.

If you need to recover the password for your old iTunes Store account you can do so by visiting http://iforgot.apple.com.