While browsing items see shipping quotes from the Postage & Shipping menu (scroll down in the item description page):

In addition, from the Purchases menu (Home -> Members Area -> Buying -> Purchases), buyers can edit the following shipping options (only if the invoice is Unpaid).

Select and open an unpaid invoice:

Edit from the invoice:

  • Shipping Address
  • Postage Method
  • and
  • Apply Insurance (optional)