Why don't you want to use the en-US version of Firefox next to the ru 6.0.2 version? In that case you only need to install an extra language pack and you can also use the same profile folder. * http://kb.mozillazine.org/Language_packs Firefox Win32 language packs: * http://releases.mozilla.org/pub/mozilla.org/firefox/releases/latest/win32/xpi/ If you use two different versions that you need to do a custom install of the other version and make sure not to start Firefox after the installation finishes. Do a custom install and install each version in its own program folder to use multiple Firefox versions. * https://support.mozilla.com/kb/Custom+installation+of+Firefox+on+Windows Create a new profile exclusively for each Firefox version.<br /> Create a desktop shortcut with -P "profile" appended to the target to launch each Firefox version with its own profile. See these mozillaZine KB articles for information: * http://kb.mozillazine.org/Creating_a_new_Firefox_profile_on_Windows * http://kb.mozillazine.org/Shortcut_to_a_specific_profile * http://kb.mozillazine.org/Using_multiple_profiles_-_Firefox

how to change language us>>ru after apply language pack? of menues I mean...

You can use this extension: * Locale Switcher: https://addons.mozilla.org/firefox/addon/356