Change the Size of My Layer Thumbnails?

In the Layers panel, Right-click in the blank area right below your Background layer (click-and-drag out the bottom of your panel, if needed). This brings up a pop-up menu where you can choose a larger or smaller size for your thumbnails (I use Large Thumbnails for mine, but that’s because I don’t use a ton of layers. It’s rare for me to have more than five or six, so I don’t mind having to scroll a bit, if I go beyond that).