Within your organization, super admins and admins are able to set new workspaces and matters to private by default. Private workspaces and matters can only be seen by members of the organization who have been invited to collaborate on these workspaces and matters by the workspace/matter owners.

This feature can be accessed only by admins in your Settings > Organization > Permissions section.

These settings change the defaults, but workspace/matter owners can still change individual items to public by clicking on one of the Share buttons in O&D.