Change private files attachment order

To sort files by alphabetical order instead of chronological order, you can use this snippet in your theme’s functions.php file.

function cuar_change_file_order_on_display($files, $post_id) { 
    uasort($files, function($f1, $f2) { 
        return strcasecmp($f1['caption'], $f2['caption']); 
    });

    return $files; 
} 
add_filter('cuar/private-content/files/the-files', 'cuar_change_file_order_on_display', 10, 2);