t3chn0 said

i already tried the solution posted here, but the problem is i cant find intl.locale.requested in my about:config so how can I change the interface language? its really annoying to have my native language, i want the english language. please help

Like it says in this article :

https://support.mozilla.org/en-US/kb/use-firefox-interface-other-languages-language-pack

You will have to add intl.locale.requested as a new preference, see :

https://support.mozilla.org/en-US/kb/about-config-editor-firefox#w_adding-changing-and-resetting-preferences

t3chn0 said

i already tried the solution posted here, but the problem is i cant find intl.locale.requested in my about:config so how can I change the interface language? its really annoying to have my native language, i want the english language. please help

The Preference is for if you have a language pack installed from https://addons.mozilla.org/firefox/language-tools/

It sounds like you downloaded Firefox in one language when you would prefer Firefox in say en-US, en-ZA or en-GB as you can download from https://www.mozilla.org/firefox/all/