You don't need an entirely new cover. If you made it yourself (or your husband) just go back to that file in the program you used and make the changes. Then save the new image as a jpeg. If a cover artist made the cover, request the new one with the corrections. They might do it free or might charge a small amount, maybe $10.
You don't need to make an entirely new document. Just make the changes in the original and save it, and then upload the new doc at the same place when you first published the book (second page for that book at your KDP account). You only need to update the information, not create an entirely new file for the book. (This would also be an ideal time to make any other changes to the doc, if you know of typos that need to be fixed.)