Hello,
When displaying the Web Interface on the logon screen, Internet Explorer uses the default user settings for language. The default language is selected based on the original locale that was used when installing Windows. To change it, you need to update the configuration of Internet Explorer.
You can configure the language for a specific computer in the registry editor or administratively for multiple computers in your Active Directory environment via Group Policies. Second method works only for all computers in a domain or in an Organizational Unit.
Let us know which way suits you better and we will provide you with detailed instructions.