Administering users is better done using a gnome tool with a gui.

Using synaptic, download and install gnome-system-tools.

This will add Users and Groups to leaf>applications>administration.

All the function of adduser, passwd and much more are available with this menu choice.

One difference I have found: Users and Groups requires passwords to be 6 or more characters,

while passwd allows a one character password, which I prefer.