Query Definition: Access List 
You use the Access List page to add collaborator information to a query definition access list. For details, see Add Collaborator.
Note
By default, no collaborators are specified for the query. In this case, all users are granted default access rights. After one or more collaborators are specified, however, other users are denied access to the query. This has the effect of hiding the query in the selection list of a query group or picker from those other users.