When you approve a post to be shared on Triberr, it schedules that post to be sent to any social networks you have assigned to the tribe that post originated in.
To change which social networks are assigned to your tribes, go to Account Settings -> Social Networks
Click on the blue button that says, “Assign Tribes”
Deselect any social network that you don’t want a post sent to when you approve a post from that tribe.
You can also do this on a post by post basis. After you approve a post, there will be a blue icon showing which social networks this post is assigned to be sent to:
Click on the social network that you don’t want the post shared to in order to deselect it: