Guess it is not in the settings implemented.
Try adding the following code to qa-chat.php right after line:
public function process_request( $request ) {
you put this code block:
// return if not at least expert
if(qa_get_logged_in_level() < QA_USER_LEVEL_EXPERT) {
$qa_content=qa_content_prepare();
$qa_content['custom0']='<div>Access forbidden</div>';
return $qa_content;
}
Hope that helps.
Kai