Each return has a delivery address where the return is sent. This will automatically be set as the address for the supplier the goods are being returned to, though it can be changed if desired.
There are a couple of shortcuts available when editing addresses.
By clicking on the Lookup button to the right of the Building field, a pop-up window will list any Delivery addresses for the account. Click on an address and it will be loaded.
If you want to lookup a post code, click on the Lookup button next to the post code. If you've already entered a suburb and state, the post codes for that suburb will be shown in a pop-up window. You can also search for a post code in that window. Click on the relevant suburb and post code listed to load that into the address.