Changed permalinks – now facebook doesn't display images when sharing

You can use the Facebook Debug Tool to retrieve new information, because there may be a caching issue with Facebook.
Just paste the URL there and see what exactly Facebook is getting.

https://developers.facebook.com/tools/debug/og/object?q=http%3A%2F%2Fwww.youexplained.com%2F4-important-habits-for-adhd-patients%2F

I’m not sure how to decipher this. Can anyone help me with it?

Everything is good, except for the image. It’s getting some avatar image from the page, instead of the featured image of the post.

I don’t know if you are using some plugin for generating the Open Graph tags or added them manually, but you should set the featured image URL as a content value in og:image.
<meta property="og:image" content="FEATURED IMAGE URL" />.

The code should look something like this:

<?php
if (has_post_thumbnail( 'single-post-thumbnail' )) :
$image = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ) );
?>
<meta property="og:image" content="<?php echo $image; ?>" />
<?php endif; ?>

Or you could use Yoast SEO which has an option for uploading and changing the content that will be shared on Facebook.