I've made a very small modification to the parent theme screenshot from the Smallbiz theme. I then created a screenshot.png file in my Smallbiz-Child folder and imported the new image into the screenshot.png file (using fileZilla).
The new screenshot is NOT showing in my smallbiz-child theme in my WP dashboard (even after hitting the refresh button). I'm a newbie at all of this and can NOT figure out what I'm doing wrong. I'm obviously missing a very simple step.
TIA for any help.