Different languages for front-end and back-end.

Hello everyone,

I tried searching the forums for an answer to my problem, but I found only very old posts that are not longer relevant. Here is my problem:

I used Codestyling Localization to translate different parts of my website, from theme files to plug-ins. Until version 4 of WordPress, I used the define( ‘WPLANG’,) string in wp-config. After I updated to version 4 of WordPress I saw the option to choose the language in the Settings menu. The problem is that I want to use a language for my front-end of the website (using the mo/po files I made with the above-mentioned plug-in) but I want the admin interface to remain in English.

If I choose English from the Settings menu, the whole website turns back to English, not just the back-end. I tried renaming the mp/po files from the /languages folder so that WordPress falls back on using the default and I temporarily succeeded , but after a plug-in update (that was unrelated to this, it was a widget plug-in) WordPress re-downloaded the language files for the back-end.

How can I force the back-end into English and still use the translations for my front-end?

Best regards,
Muad_Dib