You don't need to change language to enable this option, but if you want to add another one you just have to click Select a language to add… that I see on your screenshot. But anyway, I don't see the option that I told you previously, maybe because ESR version that you have doesn't have this option at all, or it's not under Language as on my version. As you can see, I have that option under the Language title, after the language choice.
See if typing format dates on the Settings search bar you find it, in case it doesn't it means that ESR doesn't have it. But anyway usually the websites that you use provide an option on their settings to format dates as you wish when they have many dates and times, like blogs and news websites.
