In Windows 7 Professional how to you eliminate the padlock overlay icon from multiple files? I can do it from individual files by adding the "Authenticated Users" group to the list that has full control in Security Properties
You need to change the permissions as you are and then look under advanced for the option to recourse all files and folders and replace the permissions.
You might want to read something on how NTFS permissions work to understand why you are seeing the icons and how to best deal with them. There are many resources out there but this one might be a good start.