I have struggled with this for many hours trying to follow tutorials and I'm not getting anywhere.   As you can see from the photo, I simply wish to modify this drawing by changing the curved strap to a rectangular one.  When I rotate the object the lines will not rotate with it.  When I zoom in to see if the lines have snapped to the corners, they are always a distance apart.

Please tell me how to do this (the controls), so the lines snap together and I can blend it to the original.