Users may add their own subcategories under each main category and manage their transactions in a more specific manner.
More > Income or Expense Category Management
For example,
if you wish to add a sub-category named 'Medicine' under the main category 'Health',
1) Tab the main category.

2. Tab '+' on the top right corner.

3. Type 'Medicine' and save.

You will then see 'Medicine' added under the 'Health'.

You can also change the order among the sub-categories by drag-and-dropping the '≡' icon.

After adding the sub-categories,
you will be able to track them on the entry page.
By tapping the pencil icon, you can edit the category.
