If you want to add custom moderators to your bbPress forums, use the following PHP code snippet:

<?php
function add_custom_moderators( $forum_id ) {
    $moderator_user_id = 1; // Replace with the user ID of the moderator
    bbp_add_forum_moderator( $forum_id, $moderator_user_id );
}
add_action( 'bbp_new_forum', 'add_custom_moderators' );
?>

This code will automatically assign moderators to newly created forums by specifying their user ID. Replace 1 with the actual user ID of the moderator you wish to assign.