I am having a real problem with my accounts. It appears that my password has changed, without my having done it. I had changed it once before, but that password no longer functions. I tried using my previous password, which turned out to have too many characters (what is the idea of limiting a password to eight or fewer characters?)
At any rate, when I ran into the problem with the too long password previously, it appeared that the password only included up to eight characters of the password. But no variation would work until it finally appeared to accept the longer password. Weird...
According to OS X: The Missing Manual the short name cannot be changed once the account has been created. However, apparently I can change the adminstrator password by starting up using the OS X CD, which is my next step.
These accounts and password settings caused me grief when I originally tried OS X, and now the past is coming back to haunt me!