Minifrontpage: Where does the thumbnail come from?

Dear TemplatePlazza,

Where does Minifrontpage get its thumbnail? For most of my articles it seems to pick up the first image in the body of my article (which is what I want). But for some articles it picks up the image from the "Full Article Image" parameter (which I don't want). Is there a way to tell Minifrontpage which image to prioritize between body of article, intro image, and full article image?

Thanks!

Thank you. Good to know. As a suggestion, it would be great to have an option allowing the user to choose the preferred source of the thumbnail. 

Actually the handling of the thumbnail is super annoying. I have deleted the intro image and full article image, leaving only images in the body of the article. I have also deleted the thumbnail in images/thumbnails/mod_minifrontpage. I have cleared Joomla's cache. And yet minifrontpage keeps recreating the same original thumbnail (that was previously set under "full article image") out of nowhere. How do I get rid of it?