By default the Web Access uses the same regional settings as the user's web browser. The regional settings can also be specified manually in the Web Access' settings dialog.
The user can change the E-mail Archive password. The password must meet specified complexity rules. This item is only shown if the user has the Change Password privilege and is not authenticated against an external directory service.
If your organization uses an Exchange server or Office 365 the change password will not be visible. Contact your local IT or the helpdesk for help with changing your password.