How to Control Comments for Personal Facebook Posts
You can change who can comment on your posts for both all your public posts and the select public posts. We’ll show you how to manage the options for both post types.

Manage Comments for All Public Posts
To apply a single rule as to who can comment on all your public posts, change an account-level option in your Facebook account. Start by opening a web browser on your Windows, Mac, Linux, or Chromebook computer and accessing the Facebook site. You can use the Facebook app on your iPhone, iPad, or Android phone as well.

At the top-right corner of the Facebook site, click the down-arrow icon and select “Settings & Privacy.”

From the “Settings & Privacy” menu, select “Settings.”

On the “General Account Settings” page that opens, from the sidebar on the left, choose “Public Posts.”

You’ll reach a “Public Post Filters and Tools” page. Here, next to the “Who Can Follow Me” option, click the drop-down menu and choose “Public.”

On the same “Public Post Filters and Tools” page, click the “Public Post Comments” option.

In the expanded “Public Post Comments” menu, click the drop-down menu and select who can comment on your public posts.

The available options are:

Public: Anyone, even those users who don’t follow you, can comment on your public posts.
Friends: Only your friends can post comments. If you tag someone in your post, that person and their friends can comment on your posts.
Friends of Friends: Your friends and their friends can comment on your posts.

Once you select an option, Facebook will automatically save your changes.