Understanding Folder Permissions
Permission levels on Box follow a ‘waterfall’ design in which individuals only have access to the folder they are invited into and any subfolders beneath it. More information about Waterfall permissions can be found here.
Understanding Collaborator Permission Levels
When inviting a person as a collaborator within a folder, you should use the default Invite as Editor permissions which does not allow them to share folders that have been shared with them. Refer to the following chart to review the different permissions that accompany each permission level.