For this to work you should open your archive page in FTP and add the following code

if ( has_post_thumbnail() ) { // check if the post has a Post Thumbnail assigned to it.
  the_post_thumbnail();
}

This should post a thumbnail just before your post.
Maybe edit your css a bit to make it look correct.

Good luck.

What archive page should I open?
What is the file called?
Where would I find it among the site files?
Where do I post the code provided in the page?

Can you please clarify a little for me? I appreciate it much.

When I tried the code you provided in the Archive page of my Theme, the giant image appears above the Category post summary also. I tried making the Featured Image a thumbnail size. It still stretches and posts the image giant on top of the post and appears giant on the Category page with the post summary below it.

Removing the Featured Image causes no images to appear in the Category posts summary. Whatever size the Featured Image is makes no difference. It’s stretched giant, both on the post and its category page.

What I am actually trying to achieve: A 150 pixel square image thumbnail to the left of each Post summary on its Category listing page.

Seems like it should be easy to accomplish but this ain’t doing it. This code merely posts the Post Featured Image giant on the Category listing, no matter what size the image is, it’s displayed giant in Category listing.

Screenshot of the code used, yours highlighted where I put it.

I see your theme is using the ‘content’ file.
Open the content.php or content-archive.php or anything that has something to do with content. This file is being opened to add the format of your post.

In there you should find a code which is adding the featured image.
You can alter the code over there or swap it with if {has_post_thumbnail()}{the_post_thumbnail();}

Whenever this code has been changed you can alter the visual with css.
Cheers.

I’m wondering why is the featured image being made giant at the top of the post and category and placed in the code above everything right under the header, so source code reveals nothing to me.

Simply put, I cannot write the code to make this work like I want and I know it is so simple, I need specific instructions.

Here’s the code in the Content.php file. What do I do with it?

Can you show me the rest of the code? Currently if I check the page https://musicalhelp.org/category/consorts it is showing me an archive without thumbnails but with backgrounds.

That means that the current code you are showing me (if ( has_post_thumbnails() ); is false and therefore the code after <?php endif; ?> is active.

Please add a thumbnail to one of these posts (and please tell us which post has an thumbnail assigned), after that we can check and maybe alter the code a bit to see what it does.

Thanks.

I’ve added a featured image to the Post “A New Millenium.” You’ll see the image when you visit the page and Category. It’s the top Post on Category listing page. Without this image set, the Category page only lists Post title & summary with no image. I do indeed have a background image set to the post and pages of the site so ignore that light blue n gold musical notations on page.

There you can see what is happening. If I set a featured image on the posts it displays both giant on top of the post and category listing, and displays the image actual size too below the Category listing Post summaries.

Here’s the Content.php file code:

https://musicalhelp.org/contents-page-code

We are going to use the big picture, here is the first change for the lay-out.
You will see changes happening, please do not restore before we are finished.

Add the following code in your style.css at the bottom:

/*Custom edit*/
.feature-img-box, .feature-img-box {margin-bottom: 0px!important; width: 20%; float: left;}
.entry-main {width: 75%; float: right; margin-left: 10px; margin-bottom: 50px;}
nav .post-list-pagination {position: absolute; bottom: 0; right: 50px;}
div.post-list-pagination {font-weight: bold; color: orange;}

On the archive.php file please remove the following code from the line:
if{has_post_thumbnail()}{the_post_thumbnail();}

Cheers.

The code you posted at the bottom of your message was not in the archive.php file.
I added the css you have there to the bottom of the style.css file.
Now on the Category listing page, I only have the giant image appearing on top but not the little actual size image underneath the summary.

I also have the giant featured image at the top of the post.

I do not want the giant image on the top the post. I do not want the giant image above the post summary on the Category page.

I suppose the next step is an attempt for me to adjust the sizing of these through the stylesheet (CSS) if that’s possible, unless you have something else in mind.

I wonder why the featured image is being stretched so big on the post and category? I’ve been trying to get an answer to that for 2 years which is why I don’t have any featured images set on any posts. If I can get the so called giant thumbnail to reduce, it might work out. ?? I didn’t mean to put you thru so much with this helldog2018. I hope you’ll overlook my incompetency for the moment. Just know that you are appreciated. Thanks