The dropdown menu is not working on responsive device, but does work normally on PC site. How could I solve this?

I've tried changing the setting, and found that when I set as English language on Primary menu, it does work as normal. But when I change to Thai, then it doesn't work as responsive on mobile device. (But I need they're in Thai)
How could I do with this?

Dear sir,
Could you please send us your URL link, admin account and FTP account to website information box, we will check this issue for you?

Thanks