Q: How do I switch from a U.S. iTunes Store account back to an Australian iTunes Store account?
A: There are actually a couple of different ways that you can handle this, depending on what your needs are and whether you plan to continue to shop in the iTunes Stores for both countries.
If you’re moving back to Australia after having resided in the U.S. and want to maintain a single iTunes Store account that you simply want to use in Australia, the easiest approach is to simply change the country associated with your iTunes Store account. To do this, log into your iTunes Store account settings by choosing Account from the Quick Links section on the right-hand side of your iTunes Store home page, and then when your information appears, choose the Change Country or Region link that appears below your billing address.
You will be prompted to choose a new country and will then need to provide an address in that country and an appropriate payment method that matches the country and billing address; generally a credit card or funding from a locally-purchased iTunes Gift Card will work for this purpose.
Note that if you have an iTunes Match subscription or any incomplete season passes or unexpired movie rentals you will not be able to change countries for your existing iTunes Store account. In the case of iTunes Match, you can simply cancel your subscription; for passes or movie rentals, you must wait until the pass is complete and/or your movie rentals have expired.
Changing your iTunes Store account to a different country will not affect your ability to access or play any of your existing purchased content. However, it may impact your ability to download previously purchased items from iTunes in the Cloud or update previously purchased apps.
Basically, only content that is available in your new country will be accessible from iTunes in the Cloud. Again, however, this will not affect access to anything that is already stored in your iTunes library, and in fact these items will still be available from the iTunes Store in the country where you originally purchased them should you switch back in the future.
An alternative to switching the country on your existing iTunes Store Apple ID is to setup a second, new iTunes Store account for the second country and continue to maintain both accounts. This will give you the advantage of accessing previously purchased content and app updates, but will require you to sign in and out of the different accounts in order to do so. Further, if you’re using an iOS device, remember that you can only change the account used for iTunes in the Cloud once every 90 days, making it more complicated to juggle multiple iTunes Store accounts.