Thank you for your message.
Is there a way for the user to change his/her password directly from the Viewer?
Unfortunately, changing the password for a user is only from the RU Server's Admin Console as it's a Centralized permissions management
tool that allows creating users and groups and setting access permissions globally.
However, if it's necessary for users to be able to change their passwords themselves, then please note that the RU Server's Admin Console can be installed on any machine, without the actual server service running and connected to the server service remotely as described here: https://www.remoteutilities.com/support/docs/ac-main-window/#Remote_connection
This way, users can access the server's Admin Console and change the password themselves, if necessary.
Hope that helps.