Overriding template.php files with child theme

Hi,
I copied "/Divi/includes/builder/comments_template.php" to "/Divi-Ulitmate/includes/builder/comments_template.php" and made some changes to it, but the changes don't reflect on site. If i edit the Divi-theme-files direclty it works fine.

Do i have to add something to function.php in order to reloads or change the comments_template() function?
How do i override template.php files like this, or "single.php" etc.?

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Specifically i want to achieve: if a post has "comments closed"-status, i want the comment section with "0 Comments" to be invisble. That's why i surrounded this Line in "comments_template.php" with an IF-Statement:

<section id="comment-wrap">
<?php if ( 'open' === $post->comment_status ) : ?>
<<?php echo et_core_intentionally_unescaped( $et_comments_header_level_processed, 'fixed_string' ); ?> id="comments" class="page_title">TEST<?php comments_number( esc_html__( '0 Comments', 'et_builder' ), esc_html__( '1 Comment', 'et_builder' ), '% ' . esc_html__( 'Comments', 'et_builder' ) ); ?></<?php echo et_core_intentionally_unescaped( $et_comments_header_level_processed, 'fixed_string' ); ?>>
<?php endif; ?>
...
...
Please advise.