Thanks Saguaros, everything works perfectly, in files "layout-1" and "layout-2" I changed on line 227.
The code above that didn't show the custom fields:
<?php echo HTMLHelper::('content.prepare', $this->item->fulltext); ?>
I changed it to:
<?php echo HTMLHelper::('content.prepare', $this->item->text); ?>
Now, the custom fields are displayed within the article, without problem.