The default language of LibreOffice which is English (USA) with support for Spelling check. To permanently change it follow the following steps:
- Goto Menu->Tools->Options to open the Options dialog.
- On the left side tree of choices, open Language Settings and select Languages.
- Under Default languages for documents, select the language of your choice for Western and CTL options. I selected English (UK) and Urdu (Pakistan). (Refer to the screenshot bellow)
- Press Ok and try it.