title: How to change interface language for Firefox 58, e.g. in developer tools?
body: <p>Just wondering, how to change interface language in last ff versions (58ff, 58 ff developer edition)? </p>
  
  <p>Advise "go to about:config" and change general.useragent.locale there (after switching off intl.locale.matchOS) - did not help, and I'm still have e.g. russian, but want English.</p>
  
  <p><a href="https://i.stack.imgur.com/OBSj8.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/OBSj8.png" alt="enter image description here"></a></p>