Hye NXers,
I installed Nx on hard drive, with an account A, and a password ; the absence of authentication at login is OK for me.
I wanted to create another account B to use the encryption of the personal directory, and gave the same password, this worked.
Question 1 : how can I select a user account at login ?

Then I tried to login (with account A), and change user, via the manta button/disconnect/change user, this worked too, after authentication (always same password).

Now, using account B, I tried to delete the account A via manta button//preferences/users and groups, selected user A, clicked DELETE, but then surpisingly the authentication failed repeatedly, though, I promise, I used the same password that in former steps !
Qusetion 2 : What happens ?

For your personal and most important data, like bank account, passwords and so on i would recommend to use the disk encrypter (manta->accessories->disk encrypter). it will store everything in a single file which acts like a virtual disk and is extremly safe! it uses veracrypt which is based on truecrypt and virtually unbreakable. Other advantage is: you can easily make a backup because you just need to copy a single file. And if you like to you can even send it to your email account. This way you always have a copy of your passport and other important documents in your email account. If you loose everything (maybe because the boat sunk) you just go to the next internet cafe and have your most valuable data back.

If you like to disable autologin you do this in the terminal

sudo pico /etc/lightdm/lightdm.conf

remove the line which starts with "autologin-user=" and save with ctrl+x

I'm safely home, with internet and support access, so I tried that, and ... what I feared happenned :
I answered the sudo password request in the terminal, edited the file, saved and closed the file, (^x, answered O for yes, ^X), reopened it to check the line was gone, closed it again and then rebooted.
Then came a user select windows, I selected same user, entered the password (no typo, I swear) as required, and ... authentication failed !
I tried 2 other user accounts (previously created), but encountered the same failure in authentication. (similar to point raised in my above question 2)
OK, no panic, I've used the live USB to add the removed line back to lightdm.conf, but it seems there is a real problem with users and password in Nx, isn't it ?

Just did the following: Booted from a USB Stick with the latest ISO. Made a new account using "Preferences->Users and Groups". Username "test" password "123456" to avoid confusions with keyboard layouts for different languages (my keyboard is in spanish).
And i can logout and login again as user test or even as user nx without any problem. Same with the system installed to the harddrive. Maybe you used some special characters or mixed keyboard layouts ? Also importat to note that password are case sensitive.