Just right click on the dimension and go to "Edit". There you will find a pulldown menu for the type of tolerance. Pull the menu down and select "BASIC". This will automatically put a box around the dimension. Actually that's how it's done in 11. I know INV 10 had different options when you right clicked on the dimension but I think Edit was one of them. Either way, right clicking on the dimension is where you start.
Good luck and let me know how it goes.
Powerhound
Production Supervisor
Inventor 11
Mastercam X
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II