theme update thumbs folder question

One question, when I upgrade the theme (which I will be going from non-responsive version 7.1.3 to responsive latest version), do I copy all of the images within the old themes thumb folder and paste them into the new themes thumb folder or do I actually copy the old folder itself and replace the new themes thumb folder?

I searched all over h*ll’s half acre on google and youtube and have come up drawing a blank on this simple question. I’m not techy but can follow directions or a video, unfortunately I can’t find a thing on it probably because I don’t know the correct lingo to find it?

It’s my first time attempting a theme update so let’s hope I don’t crash and burn!