When a PO is linked to a Service Ticket, then the Service Setup Defaults controls whether or not a GL Account is available on the Expense Tab.
Purchase Order
Create a New Purchase Order and select a Service Ticket.
Go to the Expense Tab and select the drop-down menu for the GL Account.
If the GL Account needed is not listed, this is controlled by the Service Setup Defaults.


SedonaSetup – Service Setup Defaults
Go to SedonaSetup and select Setup Defaults for Service.
Select the GL Accounts for the Misc Expense Tab.
The GL Accounts listed in that Section will be the only ones available in the GL Account drop-down menu on the Purchase Order.

New GL Accounts can be added to the Account List, which will then show in the GL Account drop-down menu on the PO.