Update PDF thumbnail images when files are updated/replaced?

I have a category that I am displaying on my site with the auto-generated thumbnails. Most files are never changed. However, I have just updated some files but cannot seem to get the thumbnail to update.

Outside of deleting Post and starting completely over, is there a way I can have the thumbnails match the new instance of the PDF they’re linking to?

I have even overwritten the png file directly on the server, and manually cleared the cache on the Settings page, and still the original image persists. Maybe I’m overlooking something, but I’ve tried everything I can think to try.

Thank you for your help!

Nayeem, thank you for the reply.

Perhaps I was just impatient. I checked back in on my site today, and the new thumbnails are displaying. Though the old thumbs continued to display initially, even though I manually cleared the cache, at some point over the past 10 days the cache must have cleared via automatic process and now the thumbs correctly show the new instances of each PDF.

Thanks again for taking the time to look into my issue.