@seungwoo, my question would be, if you already know the value by default, why keep an extra question (to be filled automatically)?
Else, if you still wish to prefill, you could do it as outlined in this post discussed previously:
@seungwoo, my question would be, if you already know the value by default, why keep an extra question (to be filled automatically)?
Else, if you still wish to prefill, you could do it as outlined in this post discussed previously: