Lots of people have been complaining about the removal of the "Change password" feature for clients.
I've created this free module that allows you to set a new password for your users. At the moment, you can only set passwords for the user that owns the account.
The form to change the user's password opens up in a dialogue. Success/error messages are shown in a toast.
This module is provided as-is. You're free to do whatever you want with it.
Don't expect me to fix issues - there's a chance but no guarantee.
Module can be downloaded here: https://github.com/DennisSkov/WHMCSPasswordChange/
PRs are welcome.