Default language setting for new member

I have set the default language of our forum to be Indonesian ( admin panel -> General -> Forum -> Configuration -> Board Language )

But every our new register member, their default language setting is English, not Indonesian.

Without log-in, our forum use Indonesian language as the default.
Some of our visitors are still young and not much understand English, but after they register and log-in as a new member, the board language changed to be English. They need to change their setting at their profile.

I would like to ask: Is there anyway to change our forum language default setting for new member setting? because some of our young member difficult understand to change their setting theirself.

I am not the owner of our forum, but I am one of the admins there.
Thank You very much.

bump! I want to know too

Yeah I got the same problem, but the new members on my forum gets it all in swedish, I want the defualt language to be english... I've set defualt language on english in the control panel...

Please help

Are they changing it in their profiles?

Profile>>Perferences>>Look for Lanaguage>>Pick English>>Save

I
think that is a technical update that did, because I registered a forum
English and sign up to be automatically converted to Spanish.