How to change the Admin password from blank on OS X Lion? I bought this Mac several months ago, and when it first installed by the people in the Apple store, they set the password to blank.

At first it was ok, but now I can't install any programs because the Mac keep saying that the password is incorrect. Please help me. Thanks!
In Terminal.app type passwd, this will prompt you to enter a password for your account.

Another way is to Go into Users &amp; Groups in System Prefereneces... and click on change password if possible. Not sure in the case of a blank password if that button will be active or greyed, since I never faced this situation before.