E-mail notification problem

I translated the E-mail content to local language. See example below.
ORDER_STATUS_NOTIFICATION_SUBJECT="รายการสั่งซื้อเลขที่ %s ในขณะนี้ได้ถูก %s ที่ %s"
ORDER_CREATION_NOTIFICATION_SUBJECT="รายการสั่งซื้อเลขที่ %s ในขณะนี้ได้ถูก %s ที่ %s "

One thing that I found out. After customer has placed an order, system will send out e-mail notification to customer. It was working ok for me. The content is shown in my local language. However, when I went to the Control Panel to manage order, I changed the status to, forexample, "Confirmed" and I selected the option to send notification to customer. The system sent out the e-mail notication in English. Very weird. I think I might not set something correctly. Can you please advise? Thanks.

I tried to set at the Joomla menu. Extensions->Language Manager->Administrator
I set the default to other language. I tested it again but the notification still came out in English. Did I set at the right mene?

It works now. Thanks.