Working with Dokan

If I use this script provided for dokan

add_action('woocommerce_order_status_completed', 'woocs_payment_complete', 1);
add_action('woocommerce_payment_complete', 'woocs_payment_complete');

function woocs_payment_complete($order_id) {
    if (class_exists('WOOCS')) {
        global $WOOCS;
        $WOOCS->recalculate_order($order_id);
    }
}
 
add_filter('wp_head', function() {
    if (is_page('dashboard')) {
        if (class_exists('WOOCS')) {
            global $WOOCS;
			$WOOCS->reset_currency('USD');
        }
    }
});

whenever i go back to the front side the currency does not switch to the welcome currency no matter what i do. even if i clear the cache. i am not using currency switcher.

PLease help.
Thank you