The only thing I can add is that if you'r relocating to Spain, then if you cancel the tickets, use the remaining credit to purchase some cheap $40 one way tickets from anywhere to anywhere in the US. After the change fee, whatever amount that's left over will be given to you as a paper voucher. You should (I think) be able to use these paper vouchers within a year to ticket an itinerary that doesn't necesarilly have to roiginate in the US.