Change store country on my iPad
If you go to Home screen, then into Settings, then go into iTunes & App Store.
Double-tap on the top bit where it says Apple ID: [your email address]
This will bring up your account, and it allows you to change the country.
My country (UK) showed correctly, but I re-confirmed the country and went through the several steps to save it.
After that, the iPad worked correctly for downloading updates to previously purchased Apps