featured image appears above title

so the image appears below the title

you will need to edit content.php within a child theme of Twenty Twelve;
if you already directly customized the theme itself, edit content.php in the theme, but be aware that any edits will get lost when you at any time upgrade the theme.

change this section:

<header class="entry-header">
			<?php the_post_thumbnail(); ?>
			<?php if ( is_single() ) : ?>
			<h1 class="entry-title"><?php the_title(); ?></h1>
			<?php else : ?>
			<h1 class="entry-title">
				<a href="<?php the_permalink(); ?>" rel="bookmark"><?php the_title(); ?></a>
			</h1>
			<?php endif; // is_single() ?>

to:

<header class="entry-header">
			<?php if ( is_single() ) : ?>
			<h1 class="entry-title"><?php the_title(); ?></h1>
			<?php else : ?>
			<h1 class="entry-title">
				<a href="<?php the_permalink(); ?>" rel="bookmark"><?php the_title(); ?></a>
			</h1>
			<?php endif; // is_single() ?>
			<?php the_post_thumbnail(); ?>

basically move this line
<?php the_post_thumbnail(); ?>
a few lines down to a new position.

Thank you so so much, it totally worked!

But I have two more questions (hopefully that last ones). The image is right below the title, how can I make some space between? And if possible, how can i move “write a reply” (In Danish “skriv et svar”) button so it appears below the title instead of below the image?

You can see what i mean here https://sbysofie.dk.

Thank you again!

how can i move “write a reply” (In Danish “skriv et svar”) button so it appears below the title

move the line <?php the_post_thumbnail(); ?> further down, for example to after <?php endif; // comments_open() ?>

what is the code of content.php of your child theme right now?

the <div class="comments-link"> seems to be missing?

I’m not sure I know what you mean, but maybe you’re talking about this?

<?php
/**
 * The default template for displaying content
 *
 * Used for both single and index/archive/search.
 *
 * @package WordPress
 * @subpackage Twenty_Twelve
 * @since Twenty Twelve 1.0
 */
?>

	<article id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
		<?php if ( is_sticky() && is_home() && ! is_paged() ) : ?>
		<div class="featured-post">
			<?php _e( 'Featured post', 'twentytwelve' ); ?>
		</div>
		<?php endif; ?>
		<header class="entry-header">
			<?php if ( is_single() ) : ?>
			<h1 class="entry-title"><?php the_title(); ?></h1>
			<?php else : ?>
			<h1 class="entry-title">
				<a href="<?php the_permalink(); ?>" rel="bookmark"><?php the_title(); ?></a>
			</h1>
			<?php endif; // is_single() ?>
			<?php if ( comments_open() ) : ?>
                        <?php the_post_thumbnail(); ?>
				<div class="comments-link">
			<?php endif; // comments_open() ?>
		</header><!-- .entry-header -->

		<?php if ( is_search() ) : // Only display Excerpts for Search ?>
		<div class="entry-summary">
			<?php the_excerpt(); ?>
		</div><!-- .entry-summary -->
		<?php else : ?>
		<div class="entry-content">
			<?php the_content( __( 'Continue reading <span class="meta-nav">&rarr;</span>', 'twentytwelve' ) ); ?>
			<?php wp_link_pages( array( 'before' => '<div class="page-links">' . __( 'Pages:', 'twentytwelve' ), 'after' => '</div>' ) ); ?>
		</div><!-- .entry-content -->
		<?php endif; ?>

		<footer class="entry-meta">
			<?php twentytwelve_entry_meta(); ?>
			<?php edit_post_link( __( 'Edit', 'twentytwelve' ), '<span class="edit-link">', '</span>' ); ?>
			<?php if ( is_singular() && get_the_author_meta( 'description' ) && is_multi_author() ) : // If a user has filled out their description and this is a multi-author blog, show a bio on their entries. ?>
				<div class="author-info">
					<div class="author-avatar">
						<?php
						/** This filter is documented in author.php */
						$author_bio_avatar_size = apply_filters( 'twentytwelve_author_bio_avatar_size', 68 );
						echo get_avatar( get_the_author_meta( 'user_email' ), $author_bio_avatar_size );
						?>
					</div><!-- .author-avatar -->
					<div class="author-description">
						<h2><?php printf( __( 'About %s', 'twentytwelve' ), get_the_author() ); ?></h2>
						<p><?php the_author_meta( 'description' ); ?></p>
						<div class="author-link">
							<a href="<?php echo esc_url( get_author_posts_url( get_the_author_meta( 'ID' ) ) ); ?>" rel="author">
								<?php printf( __( 'View all posts by %s <span class="meta-nav">&rarr;</span>', 'twentytwelve' ), get_the_author() ); ?>
							</a>
						</div><!-- .author-link	-->
					</div><!-- .author-description -->
				</div><!-- .author-info -->
			<?php endif; ?>
		</footer><!-- .entry-meta -->
	</article><!-- #post -->