If you move it to a client script and do onchange this might work for you.

// Global: true
// Type: OnChange
// Table: Table name you are using
// Inherited: true (this is important!)
// Field name: State

function onChange(control, oldValue, newValue, isLoading) {

if ((isLoading) || oldValue == newValue) {
return;
}
// Retrieving values from the form

// alert ('newValue ' + newValue + ', oldValue = ' + oldValue);

// Values of choice list - if not a choice list check value of field.

if (newValue == 3 || newValue == 4 || newValue == 7 || newValue == 😎 {


g_form.setValue('field you want changed', value of field of choicel list value );
if (newValue == field value or choice list value)
{
g_form.setValue('field to change','value to load with');
}
else if (newValue == 4)
{
g_form.setValue('field to change','value to load field with');
}
}