Solve the problem of not displaying thumbnails in Windows 7

Previously, in Windows 7, large icons were used to display images in the image folder, and no thumbnails were displayed, today, I found that it was in the "folder option" (the "folder option" in Windows7 is too difficult to find, and it is actually hidden in that "Organization") to set (remove "always show icon, √ of "never show thumbnail"), recalling that it was not set here before, suddenly remembered that it was previously set in "Advanced System settings" to streamline the display effect, at that time, I didn't know how to use it. I didn't find anything at the beginning. I caught it and fainted.