To edit sales:
1. Access "List Invoice" from Sales tab
2. Tap edit symbol 
on the invoice that you wish to edit
3. Select "Edit invoice" (or other options from the drop-down menu)
4. Edit the invoice information in the new screen and tap "Finish" to end process.
To edit expenses:
1. Access "List Expense" from Expenses tab
2. Tap and hold the name of expense that you wish to edit
3. Edit the expense information in the new screen and tap "Finish" to end process.