Deleting recent files in spite of AR hack to keep them persistent

Acrobat Reader DC (continuous release 2021.011.20039), my recent files are ALWAYS the same three.  They are for a product called Bromium which I don't recognize.  They are: 8rPdfFile, 8rPdfFileSmall, and 8rPdfFileLarge.  These files all urge me to get the Bromium tool.  I cannot find the files.  

There are checkboxes that allow me to select them.  There is a button to clear them.  They are gone for a moment but they're back if I open one of my pdf files and close it.  And again, the file I recently had open doesn't appear in the recent list.    Just these three.

I shouldn't have to resort to registry editing (according to another thread but the reply buttons don't work there) for the Acrobat to work as Adobe should have wanted.

I am nervous about using the registry edit as described in the other thread, as it is ten years old and my regedit version is now 21h1 and I'm way past version 10 Acrobat Reader DC.