I will explain to you how you can customize WordPress default comments yourself without using any external plugin. change comment form title “Leave a comment” to your own custom text, filter comment_form_defaults help you to change it using your theme function.php file easily.
Here is code. which you can add in your theme’s functions.php file of your active child theme (or theme).Save file.Now refresh the single post.
add_filter('comment_form_defaults', 'my_comment_title', 20); function my_comment_title( $defaults ){ $defaults['title_reply'] = __('MY CUSTOM NAME', 'customizr-child'); return $defaults; }