How to assign values in child table through client script?

ERPNext
1

why am i not able to assign value in child table?(in here the ‘Journal Entry Account’ is the child table ) , where did i went wrong?. The value can be assigned to the parent

frappe.ui.form.on(‘Journal Entry’, {
refresh(frm) {
// your code here
var b =‘hi’
frm.set_value(‘cheque_no’,b);
}
});

frappe.ui.form.on(‘Journal Entry Account’, {
on_load: function(frm) {
// your code here
var a=“aswin”;
frm.set_values(‘party_name’,a);
}
});