I must be missing something obvious here. But when I change something in the editor the changes appear in the output window to the left, but if I press the build button the changes don't appear in the new build in my browser. I've tried to refresh the browser, close the browser and allow it to open anew. I've tried deleting the previous built files, and of course saved before hitting build.
Am I missing something obvious?

Sorry, found the answer in an old post. Click restart on the new build. That seems really unintuitive though.

I'd sneer except I spend fifteen minutes, building and clicking a dead START GAME link, wondering what I'd broke. Really, doh!