PIN issue I can't resolve via Google articles -- advice welcome!

Hello forum people I don't know, who are way smarter than me about computer stuff. This is my first post, first time ever reaching out for help. Please be kind. :)

I'm running Windows 10 on a well functioning PC which I scan routinely and which I do not believe to have been compromised in any way. I protect with Avast and run Spybot from time to time. I am the owner and primary user of this computer. When I took it out of the box a few years back, I set up password access for sign on. At some point I updated from Windows 8.1 to Windows 10.

My partner rarely uses my computer but did so a few months back, after which he reported that he was prompted to set up a PIN number, to sign on. Like me, he has an advanced degree (i.e. we're not dummies), but he admitted he was confused about why that happened (given the "password as sign on" status quo), and also, about exactly what he'd done, or how to fix it going forward. Thanks, hubby.

Of course he shared this PIN number with me.

A week back I decided I wanted to go back to the password method of signing in, and while I've read and tried every single thing I found online about how to do so, I can't seem to GET RID OF the pinpad, or the need to sign in with a PIN. Feelin' kinda... not... smart... about that.

Tonight, when checking my account Settings, under PIN it actually says "Add" -- as if I don't have PIN access already set up. Which I do. I tested this by restarting my computer, and I was shown a pinpad (but no box in which to enter a password) at sign on. "Account settings \ Sign in options" still offers me the option to "Add" a PIN -- again, as if there isn't already one in place.

In case you're wondering, there's only one user account, and that's me, as Administrator.

I'm an intelligent person but admit being utterly flummoxed as to how to dump this stupid PIN thing at this point. It annoys me, but the larger issue at this point is that for all intents and purposes, I'm not able to change my sign in credentials because I can't even see that a PIN has been set up!, which over time becomes a security risk.

Anyway... stopping droning here. Do you have any help or advice to offer? It seems liks this should be such a straightforward issue, but no matter what I try, I'm not having any luck.

Thanks in advance for any suggestions. Pic of pinpad screen (my Microsoft account info redacted) attached.

(Kinda wondering if this is even the Microsoft pinpad screen at all. Maybe I AM compromised. Help!)

Kari, thanks so much for the fast and articulate reply. I appreciate you!

I understand all of what you wrote. There's still a puzzle, though: at the exact same time this pin pad thing appeared, my option to input my password at sign in disappeared. So even if this pin pad is not Windows or Microsoft, somehow, it has still taken the place as a "gate keeper" and password replacement for my computer, whenever I restart my computer.

Do you know of any software or malware that acts in place of Windows sign in, essentially replacing it? How might I figure this out?

I'm starting to wonder if my husband installed something, accidentally or purposely. I don't know what I'm dealing with here. I don't know how to resolve the problem.

😕

Kari, you're a miracle worker. I tried a reverse photo lookup but got no results so thank you for knowing how to do what I could not. Your suggestion was my fix -- thank you! Yes, I have an HP tower. I've never explored any of its password saving/sign in options (because I didn't want to!) so I didn't think to look there for an answer.

You're a miracle worker -- thank you so much for the personal assist. Can I do something for you? Cookies? Candy?

I appreciate you. :) Thanks again!