Quit/Lock password

My AAO (see current config in signature) was bought as a "return" and had been restored in the shop using a USB recovery drive. Everything works fine but I had to reset the password (sudo bash > passwd) to get to Add/Remove Programs. However if I try to change the password using Settings > Password or use the Quit > Lock facility then this password does not work. The two passwords in the BIOS are both set to "clear". While neither of these problems stop me using the AAO I am bothered by the thought that there are passwords in my box that I do not know. Any suggestions gratefully received.
Alan

 

sudo bash > passwd resets the root password
bash > passwd resets your (the user's) password
are you resetting the root password when you8 want to reset your (user) password?

 

I had not appreciated the difference. User password reset and able to use the (fairly useless) lock facility. Thanks for your help.