There are two ways to open the Device Editor.
1. Configure -> Edit Device…
This let you edit / change the devices in your current project
2. Configure->Edit Device Template
This lets you edit the devices in the device template database.
If you are developing a driver you should use the first method. In this case it is not necessary to re-import the driver. If you are finished, then you can export the driver and import it to the template database. This makes the driver available for further projects.