Wrong Windows account as administrator?

I recently helped my mom set up her laptop, we started using my Microsoft account, and now she wanted to set her own account as an administrator. So I wanted to change it the standard way. So log in to the settings with a new local account. But strangely enough, the option doesn't even exist with her! It's not as if this option is just "grayed out" (i.e. Not executable), it just doesn't exist. So I tried to set my account as the default user and not as administrator via the control panel, but that doesn't work either. If you click on Change account type, you can't select any other option as administrator! And when I just try to make another account the administrator, I go to "Manage accounts" in the control panel, as always, to select another one. And even if I added another account before, no other account except mine appears now the control panel, can someone help me?

Set up the PC again. And when you set up a new one, use your mother's Microsoft account as you should have done from the start.

But what happens to all the data that is on the PC. Once I even managed to log in with a different account, but then there were no more saved files available.

It doesn't work that way either?

https://support.microsoft.com/...915af2a34d

Even more tips, also per cmd, on the page from about the middle:

https://www.heise.de/...58638.html

Before resetting, make a "backup" on a USB stick or an external hard drive.