How can I create new categories to list my expenses accurately? I'm an artist and want to categorise my expenses into materials, promotion, printing, event fees etc.

Hello and welcome to the QuickBooks Community, sararhysillustra

The categories in QuickBooks Online are completely customizable to your business needs. To set up a new category (account in your chart of accounts):

1. Go to Settings and select Chart of Accounts.
Select New to create a new account.
3. In the Account Type dropdown, choose an account type.
4. In the Detail Type dropdown, select the detail type that best fits the transactions you want to track. Learn more about detail types.
5. Give your new account a name. Tip: Use the detail type description to create a name that describes what you're tracking.
6. Add a description.
7. If this is a subaccount of an existing account, select Is sub-account and then enter the parent account. Learn more about parent accounts and subaccounts.
8. If this is a bank account, make sure the account in QuickBooks matches your real-life bank or credit card account. Choose when you want to start tracking your finances. In the Balance field, enter the amount in the account, and determine the as of date. Enter today's date if you want to start tracking immediately.
9. When you're done, select Save and Close.

Expense categories can then be selected in the category field on an expense transaction. Here's how to enter and manage expenses in QBO for reference.

If you have any further questions, please don't hesitate to get back in touch. Have a great day!