There are two ways to reset Office 365 passwords as an administrator. Method 1 is just through a simple user interface in the administrator web portal, which is easy but not very versatile. Method 2 is through the powershell interface, and allows for far more to be done, and is also much quicker for simple password resets.
Log into the Office 365 portal as your organization’s administrator. On the left side of the page, navigate over to “Users”. The box next to the user whose password you would like to reset, then click the “Reset Password” button at the top of the page (as pictured below).
Once you click the reset button, it will take you to the next page where you can choose an email address to send the temporary password to. It defaults to the administrator email. This email is good to have but not needed if you are going to finish the password reset immediately on your own.
Once you pass this page, you move onto the “results” page where it confirms that you successfully reset the password and gives you your temporary password.
Copy this password down, then either 1) log out of the admin user and or 2) open a new web browser, and go back to mail.office365.com. Sign in as the user whose password you just reset, and paste in the temporary password (which will also be in your email if you used that option). It will open up a new screen where you will put in your temporary password, then give it a new password.
Complete this, and your password is all reset!
The second method is to reset the user passwords by powershell command. To start, sign into powershell using the normal method as covered in this earlier article. Once you are in, there are a variety of command and options, but the simplest one you can run is:
Set-MsolUserPassword -UserPrincipalName email@example.com -NewPassword TestPassword123 -ForcePasswordChange $false
In this case, “firstname.lastname@example.org” will be replaced by the user you want to reset and “TestPassword123″ is the password you are going to give it. The other handy thing you can do is reset all the passwords in your organization at once – obviously this would be a rare circumstance, but it is a good command to have non the less.
Get-MsolUser |Set-MsolUserPassword -NewPassword TestPassword123 -ForceChangePassword $True
Lastly, if you would like to set your user passwords to never expire, here is an article explaining that procedure.