Hi Thanya Wattanaphichet
Thank you for contacting and choosing our product
I think you are choosing the dropdown display menu rather than down
Please go to back-end modules -> submenu -> select "Down"
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Hope it can help you, If still having problems, Please give me link your site and your account of administrator via private message or mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
I will check it for you soon
Thanks