Font Size: It depends which Simple:Press theme you are using. If you can let me know then I can advise.

Language: Go to the firum admin > Integration > Languages and see if can download and install the French files from there…

Editor: sounds like a possible JavaScript conflict perhaps, maybe with a another plugin or your WP theme. I would need to see the forum page to be able to tell so if you can give me a link I can take a quick look.

Hello thank you for answering,

So here is my forum: www.valkyrs.fr/forum/ and i use the Reboot theme. For the language I look in “Integrations” and everything and in French: /

Firstly, your theme appears to be loading it’s own version of the jQuery UI instead of the standard version supplied with WordPress. See this FAQ for more information: https://simple-press.com/documentation/codex/faq/troubleshooting/what-is-this-jquery-conflict/

It is also loading the library called BootStrap which is completely unsupported by WordPress and can cause many problems for other plugins.

And finally, there is a specific scripting error being thrown on page load by a library called count.js which, I believe, is a part of your Disqus plugin,

Ok, can you do this for me? :/

Afraid we can’t, It is really going to come down to correcting both a WP theme and a WP plugin or changing them for ones that follow the WordPress standards and rules. Sorry.