user profile language affects my fron end language

hi,
I have a website in just one language which is Arabic i installed loco translate plugin to change some of the translations that already came with the theme .po file (adforest theme) but whenever i change the user profile in English some texts in the front end convert to English and some stay in Arabic why is that happening ? i set the site language from general to Arabic so why is the user profile language affecting the front end shouldn’t it just change the back end dashboard ?