You can add more subcategories, and customize the categories as you wish.
More > Configuration > Income / Expenses Category Management
You can change the subcategory setting on the Income/Expenses Category Setting page.
For example, you want to add "Medicine" under Health; the main category.
2. Tab the '+' button on the detail page.
3. Type "Medicine" and save.
On the entry page, you can see the sub-category added.
Also, you can access the category setting page with the pencil button.