Making files private provides an extra layer of security for confidential and/or sensitive files that you do not want to share with other people. If you make a file private, it can't be shared with other people and no one except you can download it.
To make a file private, hover over the name of the file on your My Files page, and click "make private".
To make a file public again, hover over the name of the file on your My Files page and click "make public". Please see "What are public files?" for more info.
Private files appear in red on your My Files page.