Recently, we noticed (and decided not to ignore) a helpful hint from FaceBook, pointing to a padlock icon (top-right of FB screen). Click on this icon and one of the options is 'Who can see my stuff?'
This sets the defaults for your Facebook posts which can be over-ridden for each individual post. Previously, many people had set this to friends-of-friends, which is is no longer on the initial options list - the default is now Public! To reset to friends-of-friends, use the drop-down list from Public and select Custom. Another drop-down list will enable you to select friends of friends - or to choose your preferred setting.
While you are there, take a look at the other stuff, such as 'Who can contact me?' and set as required. Of course, when FB updates, it sometimes resets settings...
You can Like our page at www.facebook.com/TheBPcUK :-)