You can not update this software since you have not owned the major version of this software.??

I have recently been having issues signing into my Apple ID and decided to go in and update my email and change my password.
Since changing my email and password I have been unable to update any of my apps. I receive this error message when trying to update, "You can not update this software since you have not owned the major version of this software."
I have looked into other forums and communities for a solution to this issue but from what I have read iTunes/Apple has yet to figure out a solution.
I have also read that the cause of this issue can be linked to two things.
One, is if you have multiple accounts on one computer. I only have one iTunes account/ Apple ID on this computer. This is my personal laptop and no one else has ever loaded on another account.
The second cause is linked to the country to which the apps were downloaded in. My computer and Apple ID were both created in the US, however 9 months ago I moved to New Zealand on a one year work holiday visa. Since living in New Zealand for the past 9 months I have been buying and updating apps, it wasn't until today when I received this error message.
I would really like to find a solution to this problem, but at the very least I would like to know what exactly caused this issue so that others may hopefully steer clear.
Any help would be much appreciated!

I think the issue is that iTunes (for whatever reason) thinks I have two Apple ID's.
also, to further complicate the issue, when i try updating the apps from my iPod the iTunes store is still recognizing my old hotmail Apple ID. So when I go to enter my password it won't accept because it doesn't match with the old Apple ID, even though it is the same account (just new Apple ID name).
I have tried signing out within the App Store and re-signing in with my Apple ID but it still brings up my old Apple ID name when I try to update.