Urgent Help Needed: Can't Update Apps on iPad...

You can buy or update apps only on the store attached to your Apple ID. Without a US Apple ID, US iTunes account, and a US-bank issued credit card you can only view in the US store.

Change the country of your iTunes Store, App Store, iBooks Store, and Mac App Store account - Apple Support

Nothing should change by changing the App Store to Australia. However, not all apps are available in all country so if you originally purchased an app from the USA store and it not available from the Australian store update will not also b available from the Australian store

Where did you purchase the Kindle books?

Per the following one can purchase Kindle books from other than the country you ae located. You have to do it viathe Kindle app, not the App Store

https://discussions.apple.com/thread/2396378?start=0&tstart=0

https://www.maketecheasier.com/purchase-ebooks-from-kindle-app-outside-of-usa/

As already said you have the change the country for the iTunes and App Store to Australia if you are located in Australia and you want to update apps.

Then you will not be able to update apps.

If you change the books already downloaded on the iPad will not be deleted

The version of your books has nothing to do with the app it has to do with the purchases you have made from Amazon that are on their server. You need to ask them if changing to the Australian Kindle App on your device will make any change with your purchased books on their site.

Your Kindle books are not related to the iTunes and Apps store. Kindle books are stored on Amazon's cloud, so you might want to give them a call and ask them if changing your iTunes & App Store on your iPad would affect you access to your Kindle books bought in the American Kindle Store, but I don't think you need to worry.

In your Kindle App, if you go to the Library and click on the set of little lines in the top left-hand corner, you will see the Settings option at the very bottom of the list that displays - tap on that. At the top of the Settings screen you will see the Registration info. Your device is Registered to your Amazon account in the Amazon Store. So, again, changing your iTunes & App Store will not affect your device registration on the Amazon site.

The books that you have purchased for your Kindle app will remain in the Amazon cloud and are accessible from any device that is registered to that account. I have my Kindle Amazon account set up on both of my iPhones, my iPad, and both of my Kindle devices. All of my books are accessible from any of them.

These are two different and separate functions, so you should have no issues. But again, you need not worry, because they will still be there in your Amazon account no matter what.

Best of luck,

GB