While entering values to split categories you have to delete the values that were automatically filled and then enter new ones. The same happens when an existing transaction is edited. You have to delete the previous amount and then only enter new amount.
It would be much more intuitive to make the old amount disappear while the new amount is entered. So we would only need to touch once the input field, and once we press numbers, they would overwrite the old ones
This is not as easy as it sounds as it might potentially cause users to remove their previously entered amounts by accident. We'll look into this though :)