From my understanding you need to use the configuration wizard again.
Once you setup , you can't move the VPN settings to another interface.
You need to choose the correct network interface and run the wizard.
Check out Lesson 3 Chapter 10 of MS Press book
Alright...I reached Lesson 3 today.
The answer to your question....it depends on what you need to accomplish!
First off, you need to create a demand-dial(VPN) interface.
Go to network interfaces node and right-click and create a demand dial interface.
Make this interface VPN and put in the proper user account and IP address.
You can go to the ports node to configure the maximum amount of connections allowed to this interface.
This make sense????
If you need more help let us know.