Hi Moore,

When this happens, there are a number of things that could be happening.  For my students, it's usually that our internet is spotty for a few seconds, so refreshing the screen or going out of the problem and then back in solves the issue.  Some people don't clear their cache/cookies enough, and that can cause minor little annoyances, like functionality of a button.  If you try both and neither fixes it, I'd suggest restarting your computer, then if it's still happening, file a support ticket: https://support.khanacademy.org/hc/en-us/requests/new 

Yes, moore2000tankie Use this https://support.khanacademy.org/hc/en-us/requests/apk link and you will get help quickly.