Change username - result: two login accounts, delete 1 unable to login

- Did a reset of Windows 10 on a virtual machine
- The default account name is then the first 5 characters of my email account
- I changed that to my real name
- Rebooted
- I was then offered 2 login accounts
- logged in using my real name
- went into account administration (Settings->Accounts-Family & Other users
- under 'Other users' removed 'Guest' (the first 5 characters)
- rebooted

Now, I was still offered two accounts, but my password did not work.
100% sure I was using the correct password and I have tried a dozen times on both accounts.
Windows then suggested to do a 'Recover your windows live account'
(account.live.com/password/reset)

But even with the new password I could not log in...

I was lucky to have a snapshot of an earlier Windows - so I restored the snapshot and Windows is running fine now.

This is a bit of a weird situation.

What if this was on a real machine?
I may need to re-install Windows from scratch. Not so much of a big issue in this case.

However... Windows will surely again offer the 5 character account, 2nd item above.
Q1: Will that then work with the new password? (the new password is combined with my full email address)
Q2: How was I supposed to proceed to avoid this?

Note that:
- on the virtual Windows (VMware) C:\Users\[AccountName] still reads the first 5 characters of my email address (outlook.com)
- on the host-pc C:\Users\[AccountName] is different , being the first 5 characters of hotmail account

Changed from hotmail to outlook.com a while ago, but the host-pc was set up at the time I was still using the hotmail account.

=

Microsoft does indeed pick the first 5 characters of your email address when setting up a new Microsoft Account login. If you create a local account first you can specify the username you want and then change it to a Microsoft account later. In that way you will keep your original [AccountName] for the user folder.

Changing the [AccountName] is very difficult, I am not sure what you did in step 3 of your post but that is most certainly where things started to go wrong.

I hope I have understood your question properly.