Attaché has 2 types of invoice aging;
Period Based aging.
Date Based aging.
The report you run to show the aging of invoices depends on the type of aging you are running.
For Period Based aging sites use Customers, Reports, Periodical, Aged Trial Balance Detailed or Aged Trial Balance Summary report, depending on whether you require just a list of the actual invoices included in each bracket or just a total amount per aging bracket.
For Date Based aging sites, use Customers, Reports, Periodical, Customer Aging Details or Customer Aged Summary report, again depending on whether you require just a list of the actual invoices included in each bracket or just a total amount per aging bracket.
Use the Invoice reminders option: Customers, Invoice Reminders, Open Invoice reminders. The All Overdue Invoices will have Invoice Balance.