I'm following the instructions to set Firefox nightly as my default browser, but when I go to settings and try to switch the toggle to "set as default browser" instead of doing it, it just opens a new tab with the instruction. I got up to 4 identical tabs before I gave up. I know how to do it, it's just malfunctioning.

In a separate issue, I have had Firefox Beta for about a year on my Kindle Fire, always worked great. Since the latest update, it won't even open. The screen pops up for a second, then immediately closes. I uninstalled and reinstalled, same issue. I installed regular Firefox, no issue. Then I found nightly, installed with no issue (other than the problem listed above).