You can change your shipping address after you place an order as long as the item has not shipped. Items are shipped as quickly as possible, so this option is usually only available until the end of the day on which you placed your order.
Note: If an item has already been processed for shipping, you will not be able to change the address.
To update your shipping address:
1. Log into your account
2. Hover your mouse over your name at the top-right corner of the site
3. Click Purchases from the drop-down menu
4. Click on Details next to the purchase
If you do not see an option to update your shipping address, it's because your order has already been processed for shipping.