Previously, when users first joined the social network, the default setting was for all updates to be "public" and visible to everyone who uses the site.
But after feedback from users, Facebook said they had decided to change this to give users more privacy.
A Facebook spokesman said: "While some people want to post to everyone, others have told us that they are more comfortable sharing with a smaller group, like just their friends.
"We recognise that it is much worse for someone to accidentally share with everyone when they actually meant to share just with friends, compared with the reverse. So, going forward, when new people join Facebook, the default audience of their first post will be set to Friends.
"Previously, for most people, it was set to Public."