Users have the ability to manually change their password, in case they login to the system by using username & password.
From within their profile page, select the "User Edit" button.
Users can set their new password using the "Password" and "Confirm Password" fields.
Then make sure to save the changes by selecting the "Submit Profile" button at the bottom of the page.
In addition, sysadmins and tenant admin can change password of specific users by first getting to their profile page.
This can be done, from the profile page of the user, or from the users page: