How to set default values for "modify entity values" form
You have to hook the form, which is shown after clicking "Modify entity values".

Here is my code to handle this:

/**
 * Implements hook_form_alter().
 */
function MYMODULE_form_alter(&amp;$form, &amp;$form_state, $form_id) {

  global $user;
  $account = user_load($user-&gt;uid);

  //to get the form id, you have to print it out first
  dpm($form_id);

  switch ($form_id) {
    case 'views_form_your_view_display_name':

      $nid_page = menu_get_object();

      // the next line activates the checkbox to show the input field
      $form['bundle_item']['show_value']['field_name']['#default_value'] = TRUE;

      // the next line sets the default value for the field shown
      // notice: the 'value' array field depends on the field type and may also
      // be 'target_id' (for entity references) or 'tid' for taxonomy references
      $form['bundle_item']['field_name'][LANGUAGE_NONE][0]['value']['#default_value'] = $your_desired_value;
  }
}