Change in Shipment Number

Hi - Usually whenever DRQJ changes in SO Revisions, shipment number changes.

I have a scenario where shipment number is changing for a partcular ship to and not changing for another ship to. Is there a setup that defines whether shipment has to change or not based on ship to

EX

Order 1001

Ship To Number  - 10

Shipment number - 1

DRQJ - 19th Jan

Now, I change DRQJ to 18th Jan and submit but shipment number does not change.

Here is another example

Order 2001

Ship To Number - 20

Shipment number - 2

DRQJ - 19th Jan

Now, I change DRQJ to 18th Jan and submit and shipment number changes from 2 to 3