Hi Margaret,
I think the squares you are referring to are the "thumbnails" under your post. These are cropped to fit that space. People can click on them to see the fullsize pictures, which are not cropped to be square.
I just went to your recent WIW and I can do this with your pictures. Photos 1 and 2 are rectangles, and photo 3 is a square. Is that different to what you uploaded? If so, there might be a bug I need to track down.
Note that with your own pictures you will also see an option to hide the photo from other people in the thumbnail. To open the picture click anywhere in the thumbnail other than this "Hide Photo" button.
The button to enlarge the picture (the one at the top right after clicking the thumbnail) only appears if the picture is too large to fit in the browser window.
I hope this helps. These things are hard to describe in words, so please let me know if anything above isn't clear.
Greg