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.