How do I migrate my Office 365 account to another Microsoft Accout

I have had my Office 365 account for many years and about 18 months ago I changed my web domain name due to some technical issues and also other reasons, and registered a new domain. Earlier this week, when my annual subscription was to be debited from my credit card, it didn't have enough funds available to complete the transaction and I received an email, to my old email address on the old domain, and I then needed to react to keep the account active. I clicked on the link in the email and was directed to my Microsoft Account and clicked on the Subscription management, which I was surprised had very little info, but an option to add a new payment method, which I proceeded with and at the point, where I needed to add my card details, my original card details appeared, and because I had transferred funds into that card to cover the subscription, I selected this card and proceeded, and the transaction succeeded. Today I got another reminder about the failed payment to started investigating and realised that what I though was my "reactivation" was actually a new subscription, linked to my new email address with my new domain, and all my shared OneDrive files are sitting on the old account and are about to expire. How do I transfer the OneDrive sharing to be registered against my new email address and then unmount all reference to my old domain, that I am actually about to cancel completely? Can anyone assist?