Hi! flora.
暖める=make the cold place to be warm 《example》 kono heya wo danbouki de atatameru
温める=make something cold to be warm 《example》 kono nomimono wo atatameru
変更する= change something in the future (schedule, reservation, menu, etc)
《example》kaigi no gidai wo hennkou suru.
ずらす= change something from A to B locally, even if it was a little bit.
also we use ずらす when to change the time to be later.
《example》tana no iti wo zurasita. / yakusoku wo 1:00 kara 1:30 ni zurasita.