How Update item on the second page in WebForm wizard I am starting to work with webform in drupal 8 and I need to show values on the second page of the webform wizard, I have reviewed several solutions but I cannot do it. I tried using $ form_state-> setValue

function webform_certificadoemail_webform_element_alter(array &amp;$element, FormStateInterface $form_state, array $context) {

  if ($form_state-&gt;get('current_page') == 'preview') {

    $value_entered = $form_state-&gt;getValue('nombre');
    drupal_set_message('Valor del nombre en el preview =:'.$value_entered); 

     $form_state-&gt;setValue('valor','This value is .......'); // This not work 
  }
}
When you are in the preview page, you're too late then. 

You need to set this in your previous step in a validate function

function webform_certificadoemail_webform_element_alter(array &amp;$element, FormStateInterface $form_state, array $context) {

   if ($form_state-&gt;get('current_page') == 'step_1') { // or whatever you called the first page
     $element['#element_validate'][] = 'webform_certificadoemail_set_valor';
  }

}

function webform_certificadoemail_set_valor($element, FormStateInterface $form_state) {
   $form_state-&gt;setValue('valor','This value is .......');
}