What do I use the set locale from accept language header site setting for?

Setting set locale from accept language headeraffect only anonyms, right? It doesn’t do anything when one is logged in.

I am not sure I understand your question, can you give more detail here? What do you mean by anonyms within Discourse?

Then speaking to the set locale from accept language header site setting, it is used to have your users register on the site with the locale their browser is set to, so they browse the community in their preferred browser set language.

Really? Because it says: ” set interface language for anonymous users from their web browser’s language headers”

Updated, you’re correct.