how do I get authentication pass word?

Normally, Ubuntu asked for the root password everytime you try to install an application from Software/Package Manager. This is a security feature which protects your system from unauthorized installations. Usually, the first configured user password equals the root password.

Hi :)

Lol, right password, wrong name. It is the normal user password that is required, the one that you might use to login to Ubuntu in the first place when the machine boots up.

The root password is something slightly different that we hardly ever need to know and would only confuse the issue in this case. For further info on that ...
https://help.ubuntu.com/community/RootSudo

Good luck and regards from
Tom :)

Yes, that would be a little misleading in my part where I typed "the first configured user password equals the root password", It's just that you can access the root account (with sudo su / sudo -i) using the first user configured password when you had not changed/enabled it using:

sudo passwd root

And if you want to disable the root account again:

sudo passwd -l root

HTH.

Lol, yep but going in as a proper root user can confuse the permissions for things so just straight sudoing the command or using the regular gui is best :)

Point taken Tom ;-)

Regards,

Ian

Hi :)

Sorry i keep trying to show off & confusing everyone. Ian's first answer works as does Bounaim's.

Apols for being pointlessly pedantic
Regards from
Tom :)