Libre Writer does not remember default language for documents

[Andras Horvath]

Steps to Reproduce:
1. Install a fresh Ubuntu 20 x64 Linux system
2. Install Libreoffice from snap
3. Open Libre Writer with a new page
4. Go to menu Tools / Language / For All Text / More...
5. Change Default Language for Documents / Western setting to Hungarian
6. Click Apply and OK
7. Close Libre Writer
8. Reopen a new page in Libre Writer
9. Language setting is not remembered even if saving the empty document before closing Writer

Actual Results:
Language setting is not remembered.

Expected Results:
Remember language settings.