This article explains how to apply Invoice date settings for sales order.
1) Please check the settings in Tools >Preferences> Replication.
2) When checked WMS Shipped date is applied as the Order date/Invoice date in MYOB, when unchecked the WMS Order Date is applied as the Order date/Invoice date in MYOB
WMS on premise
3) In addition each sale order has an override Invoice Date Function "customer Date".Check the box and select a date to force this date as the Order date/Invoice date in MYOB.