Existing child account - how to make a new Admin account

Hi. I'm getting a bit confused about how to set up child's laptop with me as an Administrator. I've read a few internet articles but they all seem to start by assuming that you have set up the computer in your own name first and are then adding a child. I put the child's name in when installing W10 and they currently have a standard user account with a password. When I go into add a family member it asks for a microsoft account email. Now presumably that is asking for the child's microsoft account email (which he doesn't have) - so I assume I don't put my own microsoft account email in there. In which case I can't work out how to set up an account as an adult admin on a family account, without creating a microsoft account for the child first. Any tips please!

By default, the user account that was set up during Windows 10 installation should be an administrative account. Windows seems to only allow to create a standard or limited account after logging into Windows. How do you know the account you've added is a standard account?

Thanks! I've gone back to Windows 7 now - there was no driver for screen resolution for that particular machine. If they start making a GMA 3600 driver I will reinstall with my own name on the computer set up and then add the child afterwards.