So Ive ordered an Apple watch series 5 LTE stainless steel gold with the Aubergine Modern buckle in Small, now im afraid that the small wouldn't fit me! Would I be able to just exchange the band in store? I know the aubergine isn't available anytime soon right now so im thinking of exchanging it with the Saddle brown modern buckle in medium. Would they let me exchange just the band or I will have to exchange the whole unit (Apple Watch and everything else)?