I can't answer that sorry. Last year there was no option to select that said you're buying to exchange. Also, you cannot exchange a black phone for a white phone. They will only exchange color for color. To change colors you need to return your phone and process as a return, and purchase the color as new. Again, this is from my experience last year.
I originally got white and they would not allow me to simply exchange for black. What I had to do was return the white, had them reset my upgrade, went phone less for a couple days until I successfully purchased one online for next day pickup. Also, when I went to pick up, I opened in the store to ensure no scratches. However, the first box was chipped, and they went to get another. 2nd box also chipped and they came out with a 3rd. By the way these were actual new boxes not the replacement boxes. Now, don't know if I got lucky and they happened to have extra black phones, or if they used those 2nd and 3rd boxes that were reserved for someone else.