Hi, when you do some changes, this will not take an effect on Google outcomes which are already there.But this still doesn't work either
To see if the change was successful, just try to visit the document/image/file directly in your browser. If you can visit this file directly in your browser, such can be indexed on Google.
There is:
1) file item - all information about file, etc. - such can be protected by access rights - when you access the file item, you will just get the info that the file you can get after login
file - the file stored on your server - which can be accessed by internet if it is not proected by .htaccess or it is not behind the public_html
In first case 1) file item is protected by Phoca Download component and Joomla! access rights. In second case 2) if the file is not behinde the public_html, then you need to add specific protection like .htaccess, etc. but then this is a question for your server, not for Joomla! or Phoca Download as in such case they are inactive and they cannot influence direct access to your server.

Jan