Can not change dropdown icon setting individually

Hi everyone

I have a struct as the following image:

There are 2 dropdowns, one is in the top level (1) and the other one is the item (2).
I want the number 1 has the icon in the left and the number 2 has icon in the right.

But if I change the icon setting of the 1, it will also change the 2 (no mater the 2’s current settings)

Do you guys has any idea? Or I did it wrong way?

Thank you.