Forgotten Office 365 admin account username and password


I have just changed my business name and wanted to go into 365 and change the details but have forgotten what my administrator account details are.

My email is currently admin@greent***** but this is not the actual administrator account. 

I guess my first question is how do I find out the login details for the administrator account and secondly is it possible to change it from @greent*** to @byt*****.au?[The information is masked by the moderator]

Thanks in advance


Hi Salim,

For the first question, you may forget to set the custom domain as primary. 
It should be: admin@greent*****

To reset password, if you had turned on self-service reset, go to

If you cannot do that, as you are the only admin in your tenant, you may Call Microsoft Support to get your login credentials.

For the second question, yes, you can, as long as you have added the new custom domain to your tenant.
Go to , find the user > find Username / Email option > Edit, add an alias using the new domain suffix, and set it as primary.

To add a domain, check this article: Add a domain and users to Office 365

* Beware of scammers posting fake support numbers here.
* Kindly Mark and Vote this reply if it helps, as it will be beneficial to more community members reading here.

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Question Info

Last updated May 16, 2021 Views 2,582 Applies to: