Conyac で依頼された翻訳結果を公開

I can't seems to change the country location on "Change country" which is found under "Shipping and handling". I do have houses in both US and Japan. However, the delivery postage shown is always calculated base on my mailing address in Japan. The fact that I couldn't change the country location, I won't be able to found out what is the delivery postage to my US address. I have asked the seller on the delivery postage (to US address), and I am told to change the country location, as well as, the zipcode (Postal code). Despite the fact that I was still able to make changes on the country location few months back, I just couldn't do it now in a sudden. Please let me know what should I do.