Accidentally changed Apple Music/App Store to USA on my iPhone, but now can't change it back
At some point it appears I clicked on something that was only available on the USA App Store or Apple Music, and in the process changed my App/iTunes Store to the USA on my iPhone.
I only realised this after I couldn't download some songs from my Music Library. It gave me this rather confusing message, which seems to say that my Apple ID is "Australian" but my Music app is set to some other country.
When I try to download an App from the App Store it get this message, which give a bit more information. I appear to be in the US store, but my "account" which I'm assuming is my Apple ID is only valid in the Australian store.
When I go to iTunes & App Store and then Apple ID and View Apple ID, and Country/Region, it won't even tell me what region I'm in, just that I can't change stores until I've spent my Apple Credit and cancelled my Apple Music subscription‽‽‽
I don't want to do that partly out of principle, but mostly because I would like to change right now rather than when I spend my balance, and cancelling Apple Music would not only stuff up my Library, but also the libraries of my 4 family members that use subscription!
Why on earth is it so easy to change stores accidentally, with no warning of the potential consequences given, but so hard to change it back‽‽‽
Some have suggested finding the website for an App only on available in the Australian store, but the only ones I've found so far just take me to the App Store and give me another error message!
Any tips on how I can get it back to the Australian Store without spending all my credit and cancelling Apple Music? I'd prefer not to restore my phone, but I assume that would do It?
I'm on a 6S running iOS13
Thanks in advance
iPhone 6s