How to change the language on the Facebook login page or in the dialog box?

I have a problem for a long time, I do not understand where the problem is. My own application and this Hackbook Demo application have the same situation when the auth popup dialog box. No matter where the web dialog or the native Faccbook app is located, I would like it to be shown in English. Even, my ios language is English, the auth dialog is still not in English.

someone help me please thanks!