How do I change the domain on my enterprise account?

You can follow along here.
https://learn.microsoft.com/en-us/microsoft-365/admin/email/change-email-address?view=o365-worldwide

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@Steven Ryan, Substance Collective

Please refer to DSPatrick's answer.

This action need to log the administrator account into Microsoft 365 admin center, such issues are not supported on Q&A forum.

If you have the further issue, I suggest you go to following forum to post a new thread.

Micorsoft 365 Answers forum --- Microsoft 365 or Office 365 for admins

Thanks for your understanding.

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Any progress or updates?

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