I think I may have discovered what's going on here. Is it true than in Design Form you specify the various widths for X-Large, Large, Medium, of the text boxes and then in Edit Form you actually select which of those widths you want to use?
If so, this answers my question. I thought that Edit Design would set what all the text boxes widths would be. It was only when using Edit Form that I discovered that each text field could be set to a different value by choosing the size which was determined during the Edit Design phase of things.
At least I think this is how it works.