There are two ways you can set users to change the password in next logon. This can be done from Exchange Management Console or Set-User cmdlet.
First lets see how to set user to change his password in next Logon.

• In Exchange Management Console, expand the Recipient Configuration node and then select the related Mailbox node.
• Double-click the mailbox entry for the user with which you want to work.
• On the Account tab, select the User Must Change Password At Next Logon check box. Click OK.

You can also use the Set-User cmdlet to perform the same task.

Syntax
Set-User -Identity ‘UserIdentity’
-ResetPasswordOnNextLogon <$false|$true>
Usage
SetUser -Identity ‘UserNameIsMrIndia’ -ResetPasswordOnNextLogon $true