How do you change the default sandbox directory?

The default sandbox directory is C:\sandbox but my C drive is almost full and I get an error message from a sandboxed program that says the J drive is full when it is not. The program needs to write large temporary files to the J drive. I’m sure the message is because the sandboxed program is writing to the sandboxed version of the J drive. How do you relocate the sandbox directory to another disk?

Update:

OK I found out that a sandboxed app writes its files to C:\VritualRoot (actual spelling, believe it or not). I tried creating a junction to redirect C:\VritualRoot to J:\VritualRoot but I got an error from the sandboxed app about writing to the J drive. Maybe I have to reboot to make this work?

I wouldn’t if it is possible to change the location of the sandbox folder. But I would suggest to clean up some on your C drive and then use EASEUS partition manager to enlarge the C partition. When done run a disk check on the changed partitions just to be sure.

The spelling error is on purpose and is to distinguish it from Sandboxie’s sandbox folder.