I finally figured out how to do this! Grab a screenshot of the Thumbs Up icon, save to your computer. Now access the WP ULike Settings page. Find “Button Icon (Unlike)” then click Select Button Icon. Upload the saved Thumbs Up icon here. Now every time someone clicks to like they’ll simply again see a Thumbs UP icon rather than a Thumbs Down.
That was driving me nuts. I hope this helps some of you as well.
Therese