Sudo su (Sorry, try again) wtf?

Question

Debian

Hello everyone, well, in general, I can’t understand something, I installed a clean one already three fucking times, I enter the password of the super user 123456789 before that I did complex ones. When I log in via ssh, the first thing I do when the system is configured is the habit of sudo apt-get update
asking for the password [sudo] password for sa:
I enter
Sorry, try again.
What's the real deal? who's lying?

Answer 1

su

Answer 2

Under root, sudo is not necessary.
If under a normal user, then you need to enter the password of the current user, not root.