This article explains how to change the "Ship Unit" field on Pack Orders screen.
Go to WMS > Tools > eBusiness > Carrier Adaptors > Settings tab
1. Under Carrier Profile, select "StarTrack"
2. Click "Services" tab at bottom
3. Highlight FFP Fixed Price Premium
4. Highlight CTN Carton
5. Click "Default"
6. It is auto saved (no additional button to click save)
==> Carton will become the default for StarTrack under Fixed Price Premium