HP Photosmart 7520 setting the scan area

Hi: I scan from my Photosmart 7520 to my iMac frequently. When a page is scanned that shows boxes of information on it, the scanner tries to put a separate scanner screen over each box. I often want the whole page scanned as one. I know how to size the scanner area to the whole page. How do I get rid of the smaller separate scans so that I don't have to deal with them?

Thanks