\label{Portfolio_ShareFile_Off}
A LON-CAPA administrator for your institution can enable or disable the setting of access controls for files in a user's portfolio space.

In your case, this feature has been disabled, so all files in your portfolio are Private, and only you can see them. The exception to this is when you select a file from your portfolio for submission to an assignment.  In that case course personnel will be able to view a locked version of the file for grading purposes.