Template blog show only last modified date

Hi,

I deleted years ago the option for showing the date in my blog and I’m trying to add the last modified date instead.

Someone suggested to add:

<?php _e('Last modified  ', 'surplus'); ?><?php if( get_the_modified_date() != get_the_date() ) echo the_modified_date();?>

I found in my single.php the following and added the code they suggested:

<article class="post clearfix">

	<header>
        <h1 class="single-title"><?php the_title(); ?></h1>
        <div class="post-meta">
            <span class="awesome-icon-user"></span><?php _e('By', 'surplus'); ?> <?php the_author_posts_link(); ?>
            <span class="awesome-icon-comments"></span><?php _e('With', 'surplus'); ?>  <?php comments_popup_link('0 Comments', '1 Comment', '% Comments'); ?>
        </div>
      <!-- <div class="post-meta">
        <span class="awesome-icon-calendar"></span><?php _e('On','surplus'); ?> <?php the_time('j'); ?> <?php the_time('M'); ?>, <?php the_time('Y'); ?>
        </div> -->
        <!-- /loop-entry-meta -->

This worked on every post page, but on the post template now is showing the date the post was created. Does someone know what I can add or change it here also to show only the last modified date:

Template-blog.php

<?php
/**
 * @package WordPress
 * @subpackage Adapt Theme
 * Template Name: Blog
 */
?>

<?php get_header(); ?>
<?php if (have_posts()) : while (have_posts()) : the_post(); ?>

<header id="page-heading">
	<h1><?php the_title(); ?></h1>
</header>

<div class="post clearfix">

<?php

query_posts(
            array(
            'post_type'=> 'post',
            'posts_per_page'=> '6',
            'paged'=>$paged
        ));

    ?>
	<?php if (have_posts()) : ?>
        	<?php get_template_part( 'loop', 'entry') ?>
    <?php endif; ?>
	<?php pagination(); wp_reset_query(); ?>

</div>
<!-- /post -->

<?php endwhile; ?>
<?php endif; ?>

<?php get_sidebar(); ?>
<?php get_footer(); ?>

Thank you!