It has been mentioned to me that Find all posts is not working even for people who have it clicked. Just thought I'd mention it since I did not see an official ticket on it here.
SirAdrian
12th August 2008, 07:54 PM
(late but oh well)
Fixed!
Under UserCP > Edit Options > Login & Privacy, you should see a new option to disable users from finding your posts. Unless this is checked, users can now search your posts.