Thanks Jenna. I can reproduce the problem occasionally. It should be a bug with change "Save" in text widget. We will try to figure out why.
Something you can try:
1. After change the color, save and refresh the Experience Builder. See if the change stays?
2. If not, do it again, save and publish. View the published app, see if changes are taken
Please let me know if it works for you.
Thanks,
Wei