function PageLoaded() {
  var str = document.body.innerHTML;
  str = str.replace('copy billing address','copy mailing address');
  document.body.innerHTML = str;
}
if(window.addEventListener) {
  window.addEventListener('load', PageLoaded, true);
} else {
  if(window.attachEvent) {
    window.attachEvent('onload', PageLoaded);
  }
}