Hey there, I'm the developer of this extension. Sorry you're having trouble. I am on Firefox 66.0.3 and it is working just fine for me. Can you further explain what issue you are running into? Have you toggled the "On" switch? Please make sure you're on the latest version of the extension - 1.1.2. Perhaps reinstall the extension again to have a fresh copy. Let me know how it goes and how I can help further. Thank you.