Set rule to run only on subfolder contents

I have been trying various combinations for hours now with no success!!
I download various files from the Internet into a nested structure of folders. My aim is to have the colour label set depending on whether I have read the file.
Starting at the top level folder, I have set it to find files that the date last opened is before the date of adding - hence it finds files I have not personally opened yet and then tell it to set the label colour to red. I have asked it to look for all subfiles and folders.
All it seems to do is set the label on the folders (it NEVER sets the label on the file itself!)
Using the Run rules on folder contents does mean that subfolders are labeled but again only the folders and NOT the files. What I want is for the files to be labeled red and the folders to be left alone.
I have very little hair left - please help before it is all gone!!!
I download various files from the Internet into a nested structure of folders. My aim is to have the colour label set depending on whether I have read the file.
Starting at the top level folder, I have set it to find files that the date last opened is before the date of adding - hence it finds files I have not personally opened yet and then tell it to set the label colour to red. I have asked it to look for all subfiles and folders.
All it seems to do is set the label on the folders (it NEVER sets the label on the file itself!)
Using the Run rules on folder contents does mean that subfolders are labeled but again only the folders and NOT the files. What I want is for the files to be labeled red and the folders to be left alone.
I have very little hair left - please help before it is all gone!!!