How to change field currency default value? Ex: USD to MMK

ERPNext
#1

cur_frm.set_df_property(“fieldname”,“default”,“MMK”);
refresh_field(“fieldname”);

Before it worked, but now it doesn’t.
Anyone can tell what i did wrong?

#2

go to “Global Defaults” and set the default currency there. No code needed.

#3

I want to change in some forms (Expense Claim multi currency), not Company Default Currency.