Installed fr-FR language for Joomla 3.6.4, made it default for site. Default for administrator is en-GB.

Downloaded and installed French language pack for K2, installed it.

Does not seem to be working for K2... for example, on the K2-User login. It still appears on the site in English. Is there something else I have to do to trigger K2 to use FR?

This is a development site (live site is in English) I have cloned to create a French version with FR Content. So the site was restored on a development server, and then I tried to change the language. Seems to be OK for Joomla core items like the Search.

My template has French language files.

Further to this, items are showing language "All", I guess I expected they would show the default, which is FR... Will I have to edit them all to show "FR"?

Which is the default language of the site?

Default is set to fr-FR for site, en-GB for administrator.

Site is a copy (bu and restore via Akeeba) on a development server.
Original is default en-GB for both site and administrator.

Make sure that the language pack's .ini files do in fact contain French strings.
If not you need to download the K2 language pack again.

Thanks for the tip about how to check. The problem was that I had downloaded and installed "French" pack and not "French - France" pack.

Once download and installed appears to be displaying front-end in Fr.

Still seems to have the language for each item listed as "All". Is there a way I can change them all to "fr-FR", or make it "default" without having to change every article?