Permissions can be set for a singular file in the Documents tab.

 

 

 1   Either right-click a document and choose Permissions, or select a document by ticking it's checkmark, clicking More Actions, and selecting Permissions.

 2   Click in the Permission column for the row of a role.

 3   Select a permissions level: Hidden, View, Print, or Download. The Manage permission level can't be changed at the file level. 

 4   Click Save.

 

To verify, click the link in the window "Go to <filename> in Permissions Tab".