Go to
Configure -> Edit Device Templates
When you usw the normal Editor, it only allows you to Export the driver, because it is stored into the project file (when you attach the vc3 file it include your moddified driver).
But when you want to Import a Driver, it is only possible for your VControl Database, and then you can add your Device Driver from the Database into the project and edit ist again and so on.
You can moddify the Templates in the Database to, but in my opinion it is safer, when you edit a driver in the project and then reimport it into you Main Database 🙂