I'm doing a little project for a my company that has recently installed SharePoint 2013.

The problem I'm having is that all domain users can Read the sites I built even though they have not been entered as Members in any SharePoint site Permission group. When I Check Permissions for such a user, it shows:
*Permission levels given to John Doe -- None.*
It then goes on with:
*The following factors also affect the level of access for John Doe*
And lists *Allow* for a dozen items. Where do I configure SharePoint so the default for users not specifically entered in a Permission group is *No Access*?