A bit off topic, but: A word of warning if you rely on preview thumbnails for finding the PDF you want in a folder of hundreds of the d**n things: DON’T install Acrobat Reader DC. It hoses all of the thumbnails and won’t let you have them back. What on earth possessed the software developers at Adobe to do that is beyond me.
The glib response from Adobe staff members to a query about this on their forum has to be seen to be believed. They lobbed the one-line response over the wall then legged it, never to be seen again. I don’t think they’d last long if locked in room with the legions of unhappy users:
Now, where did I put my Reader XI install?..