Set default directory for file uploader

I would like to give a user access to manage a specific directory on the system without using FTP. I've created a user in Webmin, but by default that user has root-level access. I've had some difficulty finding documentation on Webmin user permissions, could someone point me in the right direction? Running Virtualmin/Webmin 1.660 on Debian 7.

I found "Root directory for file chooser" but changing its value appears to have no effect on the logged-in user.

Thanks in advance!