Windows 10: only have built-in administrator account?

So yesterday i installed windows 10 on my computer and ofcourse i kept all my files.

So i logged in to a microsoft account in order to use the app store.
But when i looked, windows also used that microsoft account as email adres and name of my windows account on my pc.
But i used my brothers email-adress, so it had the wrong name.

There no option to actually log out of that specific account. So via cmd.exe i turned the built-in administrator account on and i copied all my files from the 1st account to the built-in account and removed the 1st account.

But now I don't know how to make a normal account, since this built-in account doesn't let you use edge or the app store.

When i go to settings --> account and click on "other users", it gives me the option to add someone else to this pc.
But when i click that, a window pops-up but closes itself after a less than 1 seconds.

Can anyone please help me?
I geuss the screen closes because this is the built-in account, so it's the same reason why i can't open edge etc.

But how do i create another account?
Do i just go into c:/users and add another account and copy all my stuff in there?

ps.
sorry for my english, not a native speaker.

It looks like it is a policy edit....see here: Windows 10 Edge cant be opened using the built-in administrator account — Virtualization Howto

That tweak does not work for me.

What happens when you search for and then run netplwiz? Can you add an account from there?

If not, run a command prompt as administrator and you can use:
net user username password /ADD

and then

net localgroup administrators username /ADD

obviously substitute the desire local username and password in those fields, unless you want to create an account named username :-)

I am referring to the built-in admin account not having access to edge.

What happens when you search for and then run netplwiz? Can you add an account from there?

If not, run a command prompt as administrator and you can use:
net user username password /ADD

and then

net localgroup administrators username /ADD

obviously substitute the desire local username and password in those fields, unless you want to create an account named username :-)

I am referring to the built-in admin account not having access to edge.

OK...but this isn't your thread. I was posting to the OP.