Thank you for your hint!
I looked and looked for a solution…and finally I found this:
I opened content.php, and then I moved this code:
<?php if ( has_post_thumbnail() && ! post_password_required() ) : ?>
<div class="entry-thumbnail">
<?php the_post_thumbnail(); ?>
</div>
<?php endif; ?>
right below:
<div class="entry-content">
Hopefully this is the way to do it!
Thank you so much,
Valentina
