Give the ability for users to set a password that does not expire, update when their password expires and allow a user to change their password.
Click User Accounts under Admin > Security and Users,
Select the pencil icon against the user you wish to update.
This will give you three password options that you can configure. If you are setting the users password to never expire the password expiry date will dissapear.
Please note that if the user is a Super Administrator there password will be set to never expire to ensure they are always able to log into the system.
When allowing a user to change their own password, ensure that the user has an active email address on their account for the system to send a password re-set email to.