You can change this selection at a later time by clicking the "Sharing Mode" button on the left side of your My Files page
My Files Root Folder Security
Sharing folders allows you to create browsable groups of files and images while still maintaining the privacy and security of your My Files page.
Files located within the root folder of your My Files page are only shareable one at a time. This is a security precaution to prevent anyone from accidentally gaining permanent access to all of your shared files.
When a folder is shared, all folders and files marked as "Public" within that folder are easily accessed by anyone to whom you provide the sharing link. By moving, deleting or setting that folder as "Private" you can prevent further access to your files by anyone other than yourself.