On my iTunes page, it is showing a 7 next to Apps to indicate I have 7 apps with available updates. When I click on the link to show available updates, regardless of which iTunes account I have, it always shows "No Updates are available". How can I see what apps it thinks I have updates for, or reset that counter?
The common cause of this is when you have purchases in one library that belong to two Apple ID's. You will have to sign in to that second Apple ID to download those updates. This means iTunes is working as it was designed (although it is confusing since the Apple ID for each purchase is "hidden" in the info and not easily displayed.
A less common instance is when there is a problem with either the on line store or your local files that store the apps.
Here are two articles that will help if you simply have more than one account making purchases:
Another cause for iTunes to do this is when you purchased an app in one country's store and you changed it to another country. That's what happened to me.
Updates are only available from the AppStore country you bought the app in (but the badge may still be displayed).