You can follow along here.
https://learn.microsoft.com/en-us/microsoft-365/commerce/billing-and-payments/change-your-billing-addresses?view=o365-worldwide
O365 is not currently supported here on Q&A. The product group for Office 365 actively monitors questions over at
https://answers.microsoft.com/en-us/msoffice/forum/msoffice_account
--please don't forget to upvote
and Accept as answer
if the reply is helpful--