Windows: change own password of standard user by using commandline
I have found the answer:
$oldpw = "oldpassword"
$newpw = "newpassword"
$user = $env:username
$computer = $env:computername
$user = [adsi]"WinNT://$computer/$user"
$user.ChangePassword($oldpw, $newpw)
This worked for me. Thank you for your replies!