Bank transactions entered as the wrong type
This is not the disaster you may think. Unless you have reconciled the incorrect entry. If you have then enter a "phoney" transaction that is the opposite of the transaction type, and exactly the same amount. This "cancels out" the incorrect entry - make sure this entry is described for its purpose. Enter the entry correctly, with the correct date, and then reconcile it. When you do that the balance, for the current month, will not match the balance in the bank..
If the entry has not been reconciled - delete it. Do not switch it to a different transaction type. Once it has been deleted reenter the transaction.