How to use a French dictionary occasionally?

I have LibreOffice version 5.1.3.2 installed. I have downloaded the French dictionary extension lo-oo-ressources-linguistiques-fr-v5-3 and installed it using the Extension Manager. However, I do not see French as an option in Tools->Options->Writer->LanguageSettings->Languages or Writing Aids. Also, when I do a Spell Check there is no option to select French for either Tools->SpellingandGrammar or Tools->Languages etc. How do I do a French Spelling Check for documents that I occasionally use (i.e. when I’m not writing in English, which is my normal language)? the
PS I have screenshots showing the above if required.
PPS It would be helpful if the Captcha question on this web page was in English.

Do you have restarted LibreOffice?

Yes. I also tried restarting my Ubuntu 1404 laptop.

I have tried that dictionary with LibreOffice 5.2 on Windows 7 and have no problems. I have installed it for all users". When I check the option show “Installed for all users” in the Extension Manager, it is listed there.

When I go to Tools->Options->Writer->Language Settings->Languages, I see an ABC check in front of French in the drop-down list for Western Default Language for Document. And when I click on Edit in section Available Language Modules in Language Settings > Writing Aids, I get French in the language drop-down list and see its modules.

When I open the tab Font in the character properties, I see that French has the ABC check.

If you do not get those things, I would try to remove the dictionary in the Extension Manager, restart LibreOffice and install it again. Perhaps you choose the option “for all users” as I had done?