How change "user menu" to current username
You could do that with hook_preprocess_block

e.g, in template.php

function MYTHEME_preprocess_block(&amp;$vars){

  global $user;
  $block =&amp; $vars['block'];

  if ($block-&gt;module == 'system' &amp;&amp; $block-&gt;delta == 'user-menu') {
    if (user_is_logged_in()) {
      $block-&gt;subject = check_plain($user-&gt;name);
    }
  }

}


Clear theme registry cache after adding new preprocess function.