All Agents can see all Users (Agent panel -> Users). To change this go to Admin panel -> Agents.
Click on the Agent.
Click on the Permissions tab.
Uncheck User Directory.
They should no longer be able to access the User Directory.
All agents can see Organizations (Agent panel -> Organizations). There is no setting to override this. You can change Create/Delete/Edit permissions though.
Generally speaking Agents can only see tickets if they are:
- belong to a department the agent has access to
- assigned directly to them
- belong to a team the agent has access to
To override that behavior go to Admin panel -> Agents.
Click on the Agent.
Enable Limit ticket access to ONLY assigned tickets.
Click Save Changes.