Inspired by this topic.
I recently had some trouble with sending in an assignment with canvas. At the top right hand corner I was supposed to put the date, my name, class, and assignment. The problem was that I was creating a text box on the header:
You see those right angles? Those show where the header is. When I put the content above that, it was hidden from view. The trick is to put all that <i>below</i> the header.