Join Date: Apr 2009
Location: Bye Delta
Programs: AA EXP, UA Silver, HH Diamond, IHG Plat, Hyatt Plat, Marriott Titanium, Nat'l EE, Avis PC, Hertz PC
Posts: 16,635
If you get a trip credit (which will happen if you change the existing reservation), it can be used for anyone, and it just needs to be redeemed prior to expiration.
If you get a flight credit (which may happen if you cancel the existing reservation), that’s locked to the passenger, and travel must begin by expiration.