Can't change default language

HI.

I am working on LibreOffice 5, Windows 10.
The default language for all newly created documents is set to “None” (or something similar, my program being french I don’t know the exact english equivalent)

I went to Tools>Settings>Language>Default language for documents and selected French (the french language package is of course installed on my computer), and unchecked “For active document only”.

However, every time I create a new document on LibreOffice Writer, the document language is set to None, and when I go back to Default language for documents, is still set to None, despite changing it previously.

How can I make it stick so I don’t have to change it manually every time I create a new document ?

Thanks

P.S : I have looked trough a lot of solutions, none did work.

The first solution seems to be: Reset your user profile. Shut down LibreOffice, including the Quickstarter if you still use that. Then rename the folder called “user” - important: rename it, don’t just delete it, if you have many customizations and macros.

You did that with LibreOffice closed? When you open LO after resetting the user profile, it should ask you for some personal information. If it doesn’t, the profile wasn’t reset properly.