But I haven't been able to find clear instructions about how to ensure that Windows Update has worked properly.
When I click the Start button and then then type "winver" and click "Run command", I see that I have Windows 10 Version 1803 (OS Build 17134.191)
Windows > Settings > "Update & Security" > "See what's new in the latest update", it bounces me to https://support.microsoft.com/en-us/help/4043948/windows-10-whats-new-in-recent-updates, which doesn't seem to mention security at all.
The Windows Update feature itself seems flaky, confusing, and unreliable.
I'm the most tech-savvy in my large extended family, and I generally try to help others (especially older generations) keep their systems working well, but right now I'm struggling to find a set of steps I can walk them through to confirm that their systems are no longer vulnerable.