Terminal does not accept root password (just changed it) Using dsenableroot I've just changed the password to a very simple one and terminal says 

***Successfully enabled root user.

Then I run a command with sudo and it won't accept the password I just set. 
Tried setting different passwords and opening new terminals but it doesn't help. 

What can be the problem and how do I even debug this?
You need to enter the password of the current user (who needs to be in the admin group unless you changed sudoers) if you run sudo. 

PS: as other people already mentioned in the comments: you don‘t need to enable root to run sudo, basically you don‘t need to enable it at all.