你可以用gettext 按以下方式过滤。

function rename_header_to_logo( $translated, $original, $domain ) {

    $strings = array(
        \'Header\' => \'Logo\',
        \'Custom Header\' => \'Custom Logo\',
        \'You can upload a custom header image to be shown at the top of your site instead of the default one. On the next screen you will be able to crop the image.\' => \'You can upload a custom logo to be shown at the top of your site instead of the default one. On the next screen you will be able to crop the image.\'
    );

    if ( isset( $strings[$original] ) && is_admin() ) {
        $translations = &get_translations_for_domain( $domain );
        $translated = $translations->translate( $strings[$original] );
    }

    return $translated;
}

add_filter( \'gettext\', \'rename_header_to_logo\', 10, 3 );

当没有可用的钩子时，jQuery它。。。

add_action( \'admin_footer\', \'wpse_46677_change_menu_item\' );

function wpse_46677_change_menu_item()
{
    ?>
        <script type="text/javascript">
            jQuery(document).ready( function($) {
                $("#menu-appearance").find("li:contains(\'Header\')").html(\'<a href="themes.php?page=custom-header">My Text</a\');
            });     
        </script>
    <?php
}