If the QuickBooks Online Accountant version you're using is a Australian version, once you publish your profile automatically will be listed in the Australian region.
If your business or QuickBooks Online ProAdvisor account version is in the Australian version at the moment we're unable to automatically change it to US version. You'll have to sign up for a new account under the US version. Or I'd also recommend contacting our Customer Care Team to further check your account version and region and check other possible options.