Re: How do I make make 365 my default domain exchange

Hi Nathan,

Do you mean you would like to change the default domain to your custom domain?

If so, please refer to the steps below:
1. Login to Office 365 with an administrator account.
2. Click your company name on the left-hand navigation bar.
 
3. Click Edit in the pop-up window> Change Default domain to your custom domain in the drop-down list.

If my suggestion is not applicable to your situation, please feel free to post back with more detailed information and I will be glad to help you.

Thanks,
Kevin Huang