Hi Susan, your camera shop are perfectly correct, you cannot change settings in the automatic mode on any camera. For many keen photographers the automatic mode is their "safe" option insofar as if they use this mode they will be assured of getting an acceptable result/photo. Sadly it does not allow you, the photographer, any control over shutter speed, aperture or ISO settings, so under certain circumstances, such as your project, the result is not perfect. That is why using the manual mode gives you all the control and you can set shutter speed, aperture and ISO to give you the perfect result. Moving from auto to manual takes time and it's only by making mistakes that you actually learn why things happen and how to avoid them in the future. Regards, David.