Help with Automatic Download for Apps?
Why won't my iPod allow me to turn on Automatic Downloads for Apps?
Apple Event: May 7th at 7 am PT
Why won't my iPod allow me to turn on Automatic Downloads for Apps?
What happens when you try?
Is it grayed out?
Do you have apps purchased from other than that account (Settings>iTunes and App Store) on the iPod? You have to sign into the account that purchased apps to update them.
Do you have any Restrictions set? Settings>General>Restrictions
Have you checked these articles? iTunes Store: How to enable Automatic Downloads Troubleshooting Automatic Downloads for purchased Apps, Music, and Books Automatic Downloads requires iOS 4.3.3 and above.
Help with Automatic Download for Apps?