Open qa-include/qa-page-user.php and get L59
switch (qa_request_part(2)) {
case 'wall':
qa_set_template('user-wall');
$qa_content = include QA_INCLUDE_DIR . 'qa-page-user-wall.php';
break;
and change case 'wall' something you want. Also open qa-app-format.php and get L1253
'url' => qa_path_html('user/'.$handle.'/wall'),
and change /wall to something.
Thanks to sama55