I did a deep scan for all pictures and found several hundred thumbnails which I want to securely overwrite. However, when I select them and try to overwrite, I get the message
"Not overwritten - file is already overwritten with existing file(s)". I've tried either highlighting or checking them, but it doesn't make a difference. The thumbnails can't be deleted and I can even copy them to clipboard and paste them into Paint or Word or whatever. So the image still exists.
How can I securely remove these thumbnails such that the image will not be displayed even on a deep scan by Recuva?