You define accounts in different windows of different products. To see which windows inherit accounts you define, see: Account Default Hierarchy Chart.
Exchange PO Rate Variance Gain/Loss Account. Accounting Region of the Financials Options window in Payables or Purchasing. See: Defining Financials Options.
Expense Accounts Payable Accrual Account. Defining Accrual Options Region of the Purchasing Options window in Purchasing. See: Defining Accrual Options, Oracle Purchasing User's Guide.
Inventory Accounts Payable Accrual Account. Organization Parameters window in Oracle Inventory. See: Organization Parameters Window.
Invoice Price Variance Account. Organization Parameters window in Inventory. See: Organization Parameters Window.
Other Sources
Defining Purchasing Options, Oracle Purchasing User's Guide