The Outstanding column on the Customer Transaction Enquiry window shows amounts that have not yet been allocated or have been partially allocated.
You can check what allocations exist for each transaction line as follows:
Right-click on the selected transaction
If any allocations have been made for the transaction, you will see a View Allocations option in the menu
Select View Allocations to then see the allocation history
If the View Allocations menu option is not present, it means there have been no allocations yet for this transaction
You can then use the Allocations - Allocate function to allocate the outstanding amounts, for example to allocate payments to invoices. Once all of the outstanding amounts are fully allocated and balance to zero, the Outstanding balance/total in the Transaction Enquiry window will also then show zero. Accessing the Debtors Allocations - Allocate function is as follows …
Ribbon menu style:
Select Debtors from the menu
Click on the Allocations menu icon
Select Cash Allocation from the drop down list
Classic/Module Menu style:
Select Sales Ledger from the navigation menu
Select Allocations
Select Allocate