WordPress allows you to enable/disable comments on individual blog posts, as well as across your entire site. This allows you to control which posts comments are shown on.
How to enable/disable comments on a post or page
1. Find the post in the Posts section of your dashboard, then go to edit it.
2. Click the "Screen Options" tab at the top right of the screen. Make sure the "Discussions" option is enabled.
3. Now scroll to the bottom of the page and you can enable/disable comments using the options:
It is recommended to leave the "trackbacks and pingbacks" option disabled for best results.
Comments still not displaying on some posts?
If comments are enabled on the blog post but still won't display, this may be related to the settings you are using at Settings > Discussion. Please check that you have not limited comments to within a certain date range: