Password reset for users who don't know or can't remember their passwords is done as follows:
1. Click the Site Settings gear icon at the upper right.
2. Click on User Management.
3. Search by user and see the matching profiles pop up in the "Users" area below the search box. Click on the user profile requiring password change to edit.
4. Reset the password to a temporary one and check the "Force user to change password" box.
Then Save.
On their next login attempt the user must enter the temporary password you specified above and is then prompted to type in a new password and confirm. After that, the user logs in again, with the new password.