You can reset your expired Office 365 password from any computer or mac that has a web browser on it (Chrome, Firefox or Safari).
If you go to this URL in the web browser https://outlook.office365.com and log in with your email address and your current email password.
Once logged in if your password has expired it will present the boxes below:
Enter your current password in the ‘Old password’ box and then type and confirm your own new password in the ‘Create New’ and ‘Confirm New Password’ boxes below:
Please note your new password must be at least 6 characters in length, have one capital letter and one number in it. It can also not contain part or your name or email address.
Once done click on Submit
That’s it, All reset!
You will then need to enter your new email password into Outlook after opening it, and on any mobiles, ipads etc when prompted.