featured image in category posts

Hi,
I am trying to prevent my featured images from automatically appearing at the beginning of each post. The featured image only appears when I navigate to the post from the sidebar categories menu, not when I get to the post from the carousel or search bar. I need to include a featured image because that’s the only way I can get post images to appear in the homepage carousel.
I’ve tried removing the code listed below from content-single.php as advised in a previous forum thread, but no results.
<?php if (has_post_thumbnail() )
the_post_thumbnail();
?>
Any help would be greatly appreciated.
Thanks,
Jake Moore