add_filter('generate_site_title_output', 'change_header_output');
function change_header_output() {
  return "<h1>My New Title</h1>;
}

/*** Change Header Text ***/
add_filter('generate_site_title_output', 'change_header_output');
function change_header_output() {
  return sprintf(
    '<%1$s class="main-title" itemprop="headline">
      <a href="%2$s" rel="home">
        %3$s
      </a>
    </%1$s>',
    (is_front_page() && is_home()) ? 'h1' : 'p',
    esc_url(apply_filters('generate_site_title_href', home_url('/'))),
    "Behind The <span class='header-alt-color'>News</span>"
  );
}

.header-alt-color {color: #FFF;}