At this point I am not sure exactly what worked. I thought that perhaps choosing a longer password was what did the trick, or that once I clicked apply, I then clicked logout, when I hadn't done this the first time.
But I tested things with a short password, and I was able to successfully make the change. I tested things by not clicking on logout after clicking on apply, and that wasn't what broke it either.
The only possible clue I have to offer is that when I was testing the various possibilities, I found out that my Mac laptop was holding the password somehow. By this I mean that once I submitted the password change, and deleted all cache, cookies, history, etc. from my browser, Safari, I was able to pull up the web interface *without* re-entering the password. So somehow, on my laptop, the password was being stored, even though I was clearing all browser data via the Reset Safari pull down menu. It was only when I rebooted the laptop that the password was cleared. On my iPad, the password cleared without a reboot.
The reason I mention this is that I am surmising that updating the firmware is what fixed things, but that when I tried to change the password after first updating the firmware it didn't take. That somehow the laptop was holding some old info around after I updated the firmware. And that it wasn't until I rebooted the laptop at a later time that things worked.
That is the only thing that I can come up with, as I did try to change the password after updating the firmware, and it did *not* work.