please help me, i have a problem with default os

So, my problem is:
when i bought my acpire one, it already had some password set in the store, and they didn't gave me that pass,
i wouldn't need it, but i wanted to install applications on my aspire so i needed it then.
when i tried to change password using :

i changed the password, and it didn't work

everytime i use add/remove software and type my new password, it just doesn't work.
is there a way to change this?
or is there something I'm missing?

btw everytime i try to use Terminal, and on everything i type in i get this message.

 

'sudo passwd user' will change the password for the user named 'user'

you may need to do something like 'sudo su -' followed by 'passwd' to change the administrator password

 

i know, but when i try to type sudo su pswrd etc i get this message:

I just don't know what to do.

am i missing something?

 

from what i could find online, seeing the "audit_log_user_command(): Connection refused" message is just a bug. the commands you run should still work.

 

still nothing
I'm going insain.
Is there a way to format the system to get everything to defaults and to set the password again.
like on any other pc and laptop?

 

yes, put a live linux, e.g. SystemRescueCD, or what ever, and boot from that. then mount the root partition, edit the file /etc/shadow . delete the characters between the first : and the second : following 'root'. this resets tho root password. make sure to change it after reboot.

Physical access == root access unless you use encryption

 

What happens if you just type

Code:

sudo su

?