Final answer:
To allow new users to use remote desktop services on the TargetWindowsDC01 server, the Group Policy Editor is the most suitable tool for modifying permissions.
Step-by-step explanation:
To modify permissions on the TargetWindowsDC01 server to allow new users to use the remote desktop services, the appropriate tool to use is the Group Policy Editor.
The Group Policy Editor is a management console that provides a single user interface through which all the settings of Local Group Policy objects can be managed. To enable remote desktop access for new users through Group Policy, you would navigate to Computer Configuration → Administrative Templates → Windows Components → Remote Desktop Services → Remote Desktop Session Host → Connections, and enable the policy that allows users to connect remotely using Remote Desktop Services.
Alternatively, for more granular control, Windows PowerShell can be used to modify user permissions or write scripts to automate the configuration process. However, the Group Policy Editor is the most straightforward tool for this specific task.