So I installed Debian 10.9.0, graphical install, logged in as the user I created.   

I can't do `sudo` commands with that user. (`not in sudoers group`)  

So I do `su`, type in the password.   

Then do `sudo visudo` (just `visudo` doesn't work which is weird cause I already am root...).   

I added the user to the sudoers file:   

`myuser ALL=(myuser:sudo) ALL`   

And then I try `sudo reboot` with myuser and Debian tells me:   

`Sorry, user myuser is not allowed to execute '/usr/sbin/reboot' as root on debian-desktoppc.mydomain.org.`   

Could it be that having the same password for the user and root is breaking the operating system somehow? In Ubuntu the user is not in the sudoers file as well but I can do anything with sudo there, how do they do it?