"Changing the account type" refers to change of type of an account whether it is under asset, liabiity, expense etc.
(Note that you cannot change the type of a specific account if already transaction has been completed or generated.)
Step-1: Go to Account--- Ledger Book & Select the account
Step-2: Click on the Edit Button
Step-3: Change the Account type & Click on Save Button
Step-4: Go to Settings – Configuration – PF & Gratuity
Step-5: Select Forfeited Opening Fund Account for 3 Expenses