Changing the label of Change Password Form
You have to create a new module and use hook_element_info_alter
to alter title input like this:

function my_module_element_info_alter(array &amp;$types) {
  if (isset($types['password_confirm'])) {
    $types['password_confirm']['#process'][] = '_mymodule_change_title';
  }
}


and process function

function _mymodule_change_title(&amp;$element) {
  $element['pass1']['#title'] = t('New title 1');
  $element['pass2']['#title'] = t('New title 2');
  return $element;
}


and as a result