You need to go to My Custom Programs, then create a program there. That is essentially creating a sandbox. Whn you drill into that program at the top you'll be able to choose what folders are part of this sandbox. Best way is to wildcard folder contents.
First of all, apply that to the endpoint, then run in a commandprompt: "sisipsconfig --process"
You will then be able to see if the program you want to sandbox is running, and what sandbox it is under