Since Confluence 5.5 the only supported method for storing attachments is in the file system. The attachment storage configuration screen previously provided options for customers to change where attachments are stored. This screen has no purpose in any site where attachments are already stored in the file system.
We hid this screen in Confluence 7.0 for all sites that are already storing attachments in the file system.
If you still store attachments in the database, we recommend considering migrating to the file system, as storing attachments in the database can make backing up and restoring your database more difficult.