Categories and subcategories
Categories are divided into main categories and subcategories. Each main category can contain one or more subcategories. (At least 1) Transactions and budgets are associated with a subcategory. You can manage the categories in the "Preferences" page, "Categories management" section. To move a subcategory to another main category, press on it in the "Categories management" page. Then, edit the subcategory changing the "Main category" field.