I would love to help you here but I just need some more context on your situation.
What exactly are you looking to change from American to Australian?
If you're looking for the Australian support page, you can find it here.
If you're looking to sign up to an Australian version of QuickBooks Online, you can sign up here.
Let me know if any of those links don't answer your question and I'll do my best to follow up and resolve your issues.
Cancel your QBSE US version and open a new blank QBSE AU version.
You have clicked a link to a site outside of the QuickBooks or ProFile Communities. By clicking "Continue", you will leave the community and be taken to that site instead.