Being tired of checking the “Allow comments on this post” checkbox every time I make a new post, I went into the database and changed the setting. By default, it’s set to “closed” meaning you have to check it all the time. See for yourself:
select option_name, option_value from wp_options where option_name in ( 'default_comment_status' );
Change it to “open”:
update wp_options set option_value='open' where option_name in('default_comment_status');
Now the checkbox should always be checked.