Hi and welcome Anne:
As I understand it this issue happens in video mode. Most likely you have changed the video image format from its default to a different proportion. See P53 of your manual to change this. If you don't have the manual (it should be your first port of call for any issues) you can download a copy of one as a PDF HERE
cheers, TREVOR
The mark of good photographer is less what they hold in their hand, it's more what they hold in their head;
"All the variety, all the charm, all the beauty of life is made up of light and shadow", Leo Tolstoy;
"Skill in photography is acquired by practice and not by purchase" Percy W. Harris
