Scan to preview not working properly

Question

Scanning to Preview recently stopped working properly.  Here are the issues:
When I scan a new document to Preview, it doesn't open in Preview automatically like it once did.  I begin my scan by going to "system preferences" - "print-scan" - "open scanner". 
When I click on the details section (where it says "no document loaded" above) it will open the preview window, however, the last scans made show up in the same .pdf document. 
For example: I scan 1 page to Preview, then attach that page to an email and send it.  Done.  NEXT I scan a completely separate 2 page document the same way and when I open it up with Preview, the first (1 page scan previously made) document is added to the Preview document making it a 3 page document in error.  Any suggestions to fix this?
     I've uninstalled and reinstalled the HP officejet 8500 printer, and restarted my computer and it doesn't resolve it.

Answer 1

The HP software is crap.  If is riddled through with problems and oversights.  But usually you can get things to work with enough perseverence. 
1.  Per dturner608, you can change the mode from "document feeder" to flatbed.  I did this and found that it did work that way, but I also stumbled onto something: it was working on the document feeder as well, I just didn't know it.  When you close out of the scan (after it completes), go to Finder and look for your scan file (which is usually labeled "scan") and I think you will find it there.  So the scanner is scanning, saving, but not giving you any clue that it's doing so. 
2.  There is yet another bug, which is the "one document" checkbox (it's not called exactly that), whose purpose is to make a multi-page scan into one document rather than separate pages.  Once you check that, it treats every scan from that point on like they're all one document.  Yes, incredibly that's true.  On my Mac at least, it doesn't reset itself to "zero" with every new multi-page scan.  It thinks the new scan is a continuation of the last one.  The only way I found is to trick it by doing a multi-page scan (as one document), unchecking the box and running a single page scan through that I don't intend to use, and then re-checking the box for the next multi-page scan.  That seems to tell the software that you are starting a brand new multi-page scan.
3.  Somewhere in the midst of fiddling through the above, the HP driver decided that Preview should work again.  So all of a sudden it's working - go figure.  [But I couldn't "save as".]  Like I said - their software is crap.  I've had nothing but problems with HP printer driver software.  ....Latest thing is it tells me that faxes did not go through and printing out a "fax failed" status, when in fact they did go through.  I didn't discover that until I called the recipient.  ....Spent a good half hour trying to figure out why it wasn't going through - but it was.   Nice.