Hi,

You might need to elaborate a little bit on your question, so it will be easy for us to help you.

Assuming that you are having issues about adding Serbian keyboard layout on the toolbar. Take Windows 8.1 as an example here, you can refer to this article for how to add a keyboard layout: http://windows.microsoft.com/en-us/windows-8/change-keyboard-layout

By the way, please note that this forum focuses on questions and feedback for Microsoft Office client. I'd suggest you post it to Windows forum:

https://social.technet.microsoft.com/Forums/windows/en-US/home

The reason why we recommend posting appropriately is you will get the most qualified pool of respondents, and other partners who read the forums regularly can either share their knowledge or learn from your interaction with us. Thank you for your understanding.

Regards,

Ethan Hua
TechNet Community Support