You can view Account Debts & Credits from the Web Admin.
Go to Tools -> Debts & Credits
You will be presented with a list of all your Accounts, and their Debt information.
You can select by Status and view only customers with Debt by changing the Status on top to "Credit Issue"
You can modify the values in the Obligo and Credit Allowed in Days by clicking on the field. It will become a text box.
Enter a numerical value, such as 30,60,90,etc..
You can sort by the column headings by clicking on them.
You can also enter the amount of debt by updating the Account information with debts that are past due.
Enter the amount that is past due by the time period: debts past due for >30 days, debts past due for >60 days, debts past due for >90 days.
In this example the Debts fields have been added to the Account form so that the Admin or Sales rep can update the fields.
(for instructions on how to customize the fields that appear on the Account form see this article:Account Form Layout)