If you are using OWA to read your mails, you’ll be prompted to change your password periodically when you log on to your organization’s computer network. You will be receiving notifications telling you when your password will expire. If you fail to change the password before the expiry date, you will be locked out of your mailbox.
Once you are locked out, you will have to contact your organization's helpdesk to reset your password but if your organization allows users to change expired passwords, you can follow me through the steps below to change your expired OWA password.
==> Launch your web browser to access your organization OWA URL eg https://mail.CompanyName.com/owa
==> Enter your username and the expired password
==> If the info entered are correct, you will be redirected to a page where you can change your OWA password
==> Enter your organization OWA domain and your username in the first field. This will be in the format CompanyNAme\your email address
==> Enter the expired password in the "current password" field.
==> Enter the new password you want to use in the space provided and confirm it.
NB: The new password must meet the following minimum requirements:
==> Not contain the user's account name or part of the user's full name that exceed two consecutive characters
==> Be at least seven characters in length
==> Contain characters from three of the following four categories:
--English uppercase characters (A through Z)
--English lowercase characters (a through z)
--Base 10 digits (0 through 9)
--Non-alphabetic characters (for example, !, $, #, %)
I hope this helps.