Customizable payment method
The payment methods (cash, debit, voucher) entries should be customizable. It would be very practical to be able to add/remove/edit them just like categories.
With emerging new payment method (e.g. NFC) payment with different names I think it would be easier to let user specify the name and icon rather than the dev regularly adding a new pre-existing list.
This is a standard feature in expense management program.