I have one blog with several users (some authors, some contributors). I have read under Publicize-Support that each author must connect to the Publicize service them self, but unfortunately they do not have access to the same Settings as I as Administrator. It is not possible for them to choose Settings->Sharing (Publicize).
How do get ALL posts on the blog shared on ALL the users social networking sites?
Every Author of a WordPress.com blog can publish their own posts to an individual Facebook page, that he/she is an administrator/owner. WordPress.com Publicize takes you to Facebook.com, where you need to authorize either a page or profile, where your posts are to be published. So what is required is for authors to an Administrator of that specific Facebook page.