http://www.question2answer.org/qa/18625/is-it-possible-to-hide-all-questions-for-anonymous-users
Yes. Open \qa-theme\NAME OF SELECTED TEMPLATE\qa-theme.php
insert the following code directly after the line which contains <?php
if ((!qa_is_logged_in()) and !((strpos(qa_self_html(),'login') !== false )||(strpos(qa_self_html(),'forgot') !== false ))) {
qa_redirect('login');
}else{
and add the following codejust before the end of the file (but before ?> if it contains ?>)
}