If building outlines do not match the aerial. First thing to do is to check the aerial is correctly aligned. Alignment can be checked and adjusted if there are several GPX traces otherwise best not to move any outlines. Before mapping a lot of buildings always check the aerial. see https://wiki.openstreetmap.org/wiki/Good_practicehttps://wiki.openstreetmap.org/wiki/Good_practice
EDIT jpeg of iD with all traces selected.
![alt text][1]
[1]: https://help.openstreetmap.org/upfiles/iD_and_all_traces_WiqdDbX.JPG