how to set a postgres user under windows 7

I'm trying to install postgeSQL on my win 7 machine. trying to set a password during the instalation, I found that I allready have a username named postgers in my system. can find it by typing net user postgres in the console.

Now, how can I change it's password? loged in with my administr开发者_如何学JAVAator account, I typed "net user postgres abcd123". the respond is: System error 5 have occurred. Access is denied.

What am I doing wrong? Why my admin account don't have a privilege to modify this user?

Thanks

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Try opening cmd with admin privileges explicitely (Run as administrator in context menu).