How to stop Norton's relabeling my PDFs as 'Norton HTM Document's

I recently noticed that when I try to view a list of PDF documents in my file folders using the 'Detail' view , their 'type' is shown as 'Norton HTML Documents'.  (Thankfully, when I open one of the documents, it shows it is still a PDF.) 

Why is this occurring?  How can I undo this?  I suspect (and hope) there is a setting somewhere that I can change to remove this "feature". 

I would appreciate any help.  

- Ron

Easy fix.

Go to your files in File Explorer.

Right click on any file that has a file type "Norton HTML Document".

Click "Properties".

Where is says "Opens with" click "Change..."

Select the New Default App for Your PDF Files.

Done. :)

I found a solution to my problem.  A few weeks ago I had added the "Secure Browser" from the "My Norton" section based on its promise to reduce ads.  Immediately after I downloaded it, I realized most of my pop-up ads were from Norton trying to sell me functions that I used to get as part of their basic package, so I never activated it.  On a hunch, I tried removing the Browser program from my computer and it cleared up the above "Norton HTML Document" problem. 

Why Norton felt changing the name of PDFs was necessary I do not know - was it just placing ads?  Anyway, the problem has been solved.