Make Visual Editor Default For WordPress Clients

I prefer the HTML editor view in WordPress (so I can add <h2> or <h3> titles, among other reasons) but I never want my clients to wander back there and freak out. This function makes sure that every time they add a new post, the WordPress editor opens up in “Visual” view, not “HTML” view.

function clients_default_editor() {
   $editor = 'tinymce'; // html or tinymce
  return $editor;
 }
add_filter( 'wp_default_editor', 'clients_default_editor' );