Don’t waste your time changing the scan settings for the DocuMate 3125. What you fix for one issue is sure to break something else. There is a much easier fix that goes to the heart of the problem Open your OneTouch program. I believe the default setting for button #1 is Nuance PaperPort/Auto Page HQ.
Double click on the Auto Page HQ option (or whichever one is your default). Make sure the box for “Use TWAIN driver Plus settings” is checked. You might have to tap on the unlock icon next to the configuration name box to save the configuration. Then after saving, lock the configuration again. It worked perfectly for me on the next scan and every one after.