This explains how to set up an automation that will work when more than one PO is linked with a Job/Sales Order, and therefore, you only want to move the sales order after all the POs have been received.
Create the automation
1. Click on the Cog
2. Click "Automations"
3. Click "Purchase Order"
4. Click "New Automation"
5. Give the automation a name and make it active
6. Click "Save"
Set the trigger conditions
7. Edit the first condition so the automation is triggered when the PO's status is your 'Received' status.
8. Tick to approve the edit
9. Click "Add"
10. Click here.
11. Click "Status of Siblings from Job" (or from "Sales Order", etc.)
12. Set to "Is Equal To"
13. Select "Received"
14. Tick to confirm the edit
Add the status change action
15. Select the action to fire when these conditions have been satisfied
16. Click "Change Related Job's Status"
17. Select the appropriate status for your business
18. Click "Save & Close"
19. Click "Save"
Learn more: automations in Zigaflow