You should have also 'view details' checked, and most of all, increase the thumbnail size with the zoom slider on the bottom line.
Thank you for the helpful post. Checking off View Details seems to be the secret. I really did not want to display the date and time, just the file names. However, showing both is better than nothing.
I mix JPEG and RAW files in a folder and it is not easy to tell one from the other in the thumbnail view unless you can see the file name (extension).