I mean there is a big security flaw. When someone joins, the default privacy settings are set to "everybody". This means, everything posted by every user is visible to every other member of the site. I know that users can go to the privacy tab and set the privacy settings to "My friends", but, they will never go to the privacy tab until they discover that everything they do is visible to every other users even if they are not friends!

I want to make the privacy a little bit tight so that this content is not visible by default. I mean, the user need not go to the privacy tab and set the privacy settings to "My Friends". It should be set by default.

Is there a way I can edit some configuration file or edit the source code to set these defaults?