When making a new post, by default it will post to the 'Friends' privacy group, however if I click the lock icon, the 'Public' group is already selected instead of 'Friends'. Also, in order to actually change the privacy group of the post to 'Public', I have to select a different group and then select 'Public' again.
 UI  bugs
I just realised, I deleted my 'Friends' group. That must be the reason why - the default privacy group to post to is still set to the 'Friends' group, even though it's deleted, and since that group doesn't appear in the dropdown list, it just defaults to the first list item, which is 'Public'.
  last edited: Mon, 04 Sep 2017 15:42:38 -0400  
I fixed it by changing Default Access Control List to one of my existing groups. (I think 'Access Control List' is the old term for 'Privacy Group', so I think the name should be changed to 'Privacy Group' in the settings page to save confusion.)
Right, the button should probably be labeled "Default privacy group".