Budgets comprise two elements, an estimate of costs and actual expenditure. Estimates are entered and edited with tasks, each task has an optional cost which may be positive or negative (you may make spend or make money).
When you look at the budget view you see a list of these estimates by date. Selecting an estimate will open its parent task for editing, however you cannot delete an estimate – instead set it to zero.
Also from the budget view you can add actual costs or income. These have an optional narrative and are associated with a task. Actuals can be deleted from the budget view using the Edit menu.
Rotating the phone will change the display to a report showing costs per day and cumulative costs for each plan.