change single post template in custom post type

add_filter( 'jnews_single_post_template', 'change_single_post_template', 99, 2 );


function change_single_post_template( $template, $post_id ) {
    if ( 'private-post' === get_post_type( $post_id ) ) { /* change with your custom post type */
        $template = 3; /* change with number of single post template you want */
    }
    return $template;
}