At the moment, we have no way to edit product settings en-masse; they can only be edited manually, one at a time. Development is aware of the demand for a mass-edit feature, so that may come eventually.
If you're changing the directory name as a security measure, you might consider other, more secure methods than "security by obscurity". For instance, if your site is hosted on a typical Apache-based server (as most are), you can reject all attempts to access files in that folder if the connection doesn't come from a server on e-junkie.com -- just add a text file named ".htaccess" inside the downloads folder, with these directives listed in that file:
<limit GET>
satisfy any
order allow,deny
Allow from e-junkie.com
</limit>
<limit POST>
satisfy any
order allow,deny
Allow from e-junkie.com
</limit>