Sign in to Office 365 with your work or school account.
Go to Settings > Password.
Type your old password, and then type a new password and confirm it.
Some users can’t change their password in Office 365 because their organization creates and maintains their accounts. If you don’t see a link to change your password, then your organization is blocking you from changing it.
Forgot your password?
If you forgot your work or school account password or it’s no longer working, go to the self-service password reset tool.
If your admin hasn't enabled self-service password reset, use the password reset tool to send a request to your Office 365 admin or workplace technical support to reset it for you.