Default Accounts in Procure to Pay flow

 Hi Folks,

while using Procure to pay process flow, where system will pick the accounts .

1) Receiving Account

2) AP Accrual Account

3) Charge Account (For expense Item)

4) Material Valuation Account (for Inventory Item)

5) Asset Clearing Account (for asset item)

6) Budgetary Account (Encumbrance Used)

7) Reserve for Encumbrance Account(Encumbrance Used)

please explain each account in detail manner, i.e where we will enter this account in our setup part, what are stages it can be override