Need Help Changing Default Login

I don't know how my aunt managed to foul things up on her Windows 10 Home tower, but when she powers on the unit she gets a screen with her user name, Joan, and the little figure shown here, accompanied by the phrase 'The user name or password is incorrect. Try again'. At this point she has done nothing but press the power button. And no place has displayed to even enter a password.

There is a little box labeled OK under the message. Pressing that opens a box under her name for the password. It also opens other user names at the bottom left of the screen, one of which is also labeled Joan. However, that particular 'Joan item' has her personalized user picture. Clicking on that brings up the name Joan with her picture and a password box. She can then enter her password and get into Windows.

If she enters her password in the box with the above stick figure it doesn't work. She has to click on the other Joan user with her picture before she can access Windows.

How can we get this to NOT bring up the stick figure Joan, which may be a Microsoft account (or not, my aunt doesn't know anymore), or delete the stick figure Joan, or do whatever is necessary to get her name, picture and password be the default?

I have, of course tried running 'control userpasswords2', checking, saving, reopening, unchecking and saving again. No change.