FrontendUser::setPassword() 

\nn\t3::FrontendUser()->setPassword($feUserUid = NULL, $password = NULL); 

Change the password of an FE user. Alias to \nn\t3::FrontendUserAuthentication()->setPassword().

\nn\t3::FrontendUser()->setPassword( 12, '123password$#' );
\nn\t3::FrontendUser()->setPassword( $frontendUserModel, '123Password#$' );

| @return boolean

public function setPassword( $feUserUid = null, $password = null )
{
	return \nn\t3::FrontendUserAuthentication()->setPassword( $feUserUid, $password );
}