How do I bring back my thumbnail preview in file explorer?

I am running on Windows 10. My pdf's have always shown a preview of the pdf on file explorer. I recently changed my default program for pdfs to Adobe Reader 9.5. Now, however, I can't see previews of the document as the thumbnail. I have looked all over the internet and have not found a solution. Most solutions are for Acrobat which I don't have so under view - general I do not have the option to enable thumbnail previews. Is there a way to do this for Adobe Reader 9.5?