change save button text of a node to submit
This is the complete $form['actions']['submit'] array the Node module uses for the form.

  $form['actions']['submit'] = array(
      '#type' =&gt; 'submit',
      '#access' =&gt; variable_get('node_preview_' . $type, DRUPAL_OPTIONAL) != DRUPAL_REQUIRED || (!form_get_errors() &amp;&amp; isset($form_state['node_preview'])),
      '#value' =&gt; t('SaveTest'),
      '#weight' =&gt; 5,
      '#submit' =&gt; array('node_form_submit'),
   );


You need to hook into the node form.

/**
 * Implements hook_form_alter().
*/
function MYMODULE_form_alter(&amp;$form, $form_state, $form_id) {
  if (isset($form['#node']) &amp;&amp; $form_id == YOUR_NODE_TYPE . '_node_form') {
    $form['actions']['submit']['#value'] = t('YOUR_NEW_VALUE'),
  }
}