Here is the full article from Microsoft: https://support.office.com/en-us/article/Your-account-settings-are-out-of-date-4484de9e-66b2-46a9-84...
Here are quick instructions:
The most common cause of an out-of-date account is an incorrect password.
Choose Fix account in the notification bar at the top of the Mail or Calendar app.
If your password is incorrect, you'll see a message asking you to update your password.
Enter the new password and choose Done.
You may also want to check the box that says "remember password" just in case.
I hope this works for you!