Configuring Self Service Password Reset
You may be prompted on sign in to www.office.com that 'More information is required' for your account, alternatively you can navigate to https://account.activedirectory.windowsazure.com/passwordreset/register.aspx to start the registration process.
Clicking Next will take you to the following screen. You may be asked to enter your current password to continue.
Click 'Set up now' next to the Authentication Phone. This will ask you to enter your mobile number and subsequently send a one time code which needs to be entered on the page.
Do the same for the Authentication Email Address.
Once this has been completed click Finish to complete the process