Set a default sharing restriction for Google+ content
You can control whether your users' posts can be shared outside your organization by default. If a post is restricted, people in your organization who receive it can't share it with anyone outside your organization.
If you restrict sharing posts, other Google+ content is also affected. New communities are restricted to your organization, by default, and users' +1 notifications are always restricted.
To restrict user content to your organization by default:
Sign in using your administrator account (does not end in @gmail.com).
From the Admin console dashboard, go to AppsAdditional Google ServicesGoogle+.
Click Advanced Settings.
- In the Sharing posts section, select Make the default setting for new posts restricted.