From your web browser go to www.office.com.
Click Sign In.
Type in your new email address.
Type in your password.
Set up two factor authentication for a walkthrough click -> here.
Download the Microsoft Authenticator App on your phone.
Select allow notifications.
Choose work or school.
Scan the QR code on your computer monitor.
Click Next on your computer after the Authenticator App is set up.
When prompted , scan the barcode.
Select Approve Sign In.