Parent and Child
Accounts and categories can be the “Parent” of another account or category of the same type.
For example, the expense category Bills could be the "Parent" of the expense categories Electric, Gas, and Phone.
This means the expense categories Electric, Gas and Phone are "Child" categories (also known as sub-categories) of the expense category Bills.
When creating a new category via Tools > Categories > New, you can specify the "Parent Category".
When creating a new category, if a category is highlighted when you select "New", the highlighted category will be assigned as the "Parent" of your new category. You can change the "Parent Category" field when amending the new category details.
To edit an existing category, choose Tools > Categories, then double-click on the category you want to change, or highlight the category name and choose "Edit".
Parent categories must be the same category type as the child category.
e.g. An Expense category cannot be the parent of an Income category..
If the parent category is assigned as the "Base" account, then you will be creating a new parent category, to which subcategories can be created or assigned.
The "Base" account is the first option in the drop-down list, that displays a purple stack of coins icon. The base account is the name of your data file. In the screenshot below, the base account is called "My Finances".
When creating a new account via Account > New Account, you can specify the "Parent Account".
To edit an existing account, select your account and choose Account > Edit account.
Parent accounts must be the same account type as the child account.
E.g. A bank account cannot be the parent of a credit card account.
The only exception to the Parent/Child feature is Investment accounts - they cannot be the parent or child of another account.