function wishlist_premium_defaults() {
    if (!get_option('wish_list_premium_first_active')) {
            update_option('yith_wcwl_use_button', 'yes');
            update_option('select2-yith_wcwl_add_to_wishlist_icon-container', 'select2-yith_wcwl_add_to_wishlist_icon-result-glje-fa-heart-o');

            add_option('wish_list_premium_first_active', 'true');
        }
    }
}

add_action('init', 'wishlist_premium_defaults');