Change order by date on category wordpress - php

Question

I need help with a product category page in Wordpress. Original code was made by someone else, and I'm fairly new to php. I may need help with looking for a way to make the product sort by date published. right now, here is the code that I have.
category-books.php
<?php
/**
* Template Name: Store Template
* #package WordPress
*/
get_header(); ?>
<div id="page-title">
<!-- 960 Container Start -->
<div class="container">
<div class="sixteen columns">
<h1>
<?php single_cat_title( '', true ); ?>
</h1>
</div>
</div>
<!-- 960 Container End -->
</div>
<?php
get_template_part( 'content', 'product4' ); ?>
<div class="blogsidebar" style="float:left !important">
<?php dynamic_sidebar('sidebar-1'); ?>
</div>
<?php get_footer(); ?>
content-product4.php
<?php function bac_wp_strip_header_tags_only( $excerpt ) {
$regex = '#(<h([1-6])[^>]*>)#';
$excerpt = preg_replace($regex,'', $excerpt);
return $excerpt;
}
add_filter( 'the_content', 'bac_wp_strip_header_tags_only', 0); ?>
<div class="container">
<?php $sidebar_side = get_post_meta($post->ID, 'incr_sidebar_layout', true);
if($sidebar_side == "left-sidebar") {
get_sidebar();
} ?>
<!-- Blog Posts ================================================== -->
<div class="twelve columns" style="float:right !important;">
<div class="product-container">
<?php $posts = query_posts($query_string . 'orderby=date&order=DESC&cat=238'); ?>
<?php while (have_posts()) : the_post(); ?>
<!-- Post -->
<div <?php post_class('post'); ?> id="product-post-2Col" > <a class="post_title" href="<?php the_permalink() ?>">
<div style="margin-bottom:10px;width: 130px;height: 180px !important; border: 2px solid #000 !important;padding: 3px;float: left;margin: 0 15px 15px 0;overlay:hidden;">
<?php if ( has_post_thumbnail() ) {
the_post_thumbnail( 'medium', array( 'class' => 'store-featured-image' ) );
} else { ?>
<img src="<?php bloginfo('template_directory'); ?>/images/product-image.png" alt="<?php the_title(); ?>" />
<?php } ?>
</div>
<div style="min-height:40px !important;width:50% !important;float:left;">
<h4>
<?php the_title(); ?>
</h4>
</a> </div>
<?php?>
<div class="product-description-2col">
<?php the_excerpt()?>
<a style="margin-bottom: 8px;" class="post_title" href="<?php the_permalink() ?>">Learn More</a><br/>
<?php ?>
<a href="<?php the_field('buy_now_1')?>">
<div id="buybtn">Buy Now</div>
</a>
<?php ?>
</div>
<?php ?>
<p> </p>
<p> </p>
</div>
<!-- Post -->
<?php endwhile; // End the loop. Whew. ?>
</div>
<div style="text-align:center;">
<?php posts_nav_link( ' · ', 'previous page', 'next page' ); ?>
</div>
</div>
<!-- eof eleven column -->
is there a way to add something to functions.php? I've added this line but still not working:
<?php $posts = query_posts($query_string . 'orderby=date&order=DESC&cat=238'); ?>
<?php while (have_posts()) : the_post(); ?>
Thanks for the help.

Answer 1

Instead of using functions.php for this, create a child theme and edit a copy of the file you want to change there.
https://codex.wordpress.org/Child_Themes