silverstripe-comments/docs/en/Configuration.md

Configuration

The module provides a number of built in configuration settings below are the default settings

// mysite/_config.php 

Commenting::add('Foo', array(
	'require_login' => false,
	'required_permission' => false,
	'use_ajax_commenting' => true,
	'show_comments_when_disabled' => false,
	'order_comments_by' => "\"Created\" DESC",
	'comments_per_page' => 10,
	'comments_holder_id' => "comments-holder", 
	'comment_permalink_prefix' => "comment-",
	'require_moderation' => false
);

If you want to customize any of the configuration options after you have added the extension (or on the built-in SiteTree commenting) use set_config_value

// mysite/_config.php - Sets require_login to true for all pages
Commenting::set_config_value('SiteTree', 'require_login', true);

// mysite/_config.php - Returns the setting 
Commenting::get_config_value('SiteTree', 'require_login');