Select "Profile" from the menu on the upper left part of your screen. If you've accidentally chosen a language you don't understand, just select the fourth item from the left.
You will be shown a screen with two options below the main menu. T first one is "Profile Info", the second is "Modify Profile" - in whatever your current language is. Select the second one.
A screen will show up displaying your account setttings the last one at the very bottom is the language setting.
I hope that helps.