Solution

<?php if ($comments) : ?>

	<ol>

	<?php foreach ($comments as $comment) : ?>

		<li id="comment-<?php comment_ID() ?>" class='comment'>
			<!-- the comment data -->
		</li>

	<?php endforeach; ?>

	</ol>

<?php endif; ?>

The code above is an ordinary comment check and loop. $comment is an array that holds all the comments ordered from oldest to newest. Using a built-in php function array_reverse() we can easily change the order to be from newest to oldest.

<?php if ($comments) : ?>

	<? $comments = array_reverse($comments); ?>

	<ol>

	<?php foreach ($comments as $comment) : ?>

		<li id="comment-<?php comment_ID() ?>" class='box2 commentItem <?=$authorClass?>'>
			<!-- the comment data -->
		</li>

	<?php endforeach; ?>

	</ol>

<?php endif; ?>

And now we got our comments ordered from newest to oldest, with just one simple function.

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