Hi accounting-futur,

Welcome to Community!  QuickBooks Online is an exceptional accounting software providing everything you need to reach your bookkeeping goals.  Having the ability to apply default options is a great time saver.  I'll be happy to provide more information so you can reach your QuickBooks goals with confidence!

When you set up a supplier you can add an opening balance and a default expense account.  However, based on the information you've provided, when creating an invoice, you can also set a default account to your products and services.  Here's how:

1. From the Gear in the top right, select Products and services

2. Locate the product/service in the list and hit Edit in the Action column

3. Enter the Sales price, Income account and applicable Sales tax

4. Under Purchasing Information enter a Description, Cost and default Expense account

5. Select the applicable Sales tax and hit Save and close when finished

If you require additional assistance or have other questions, please don't hesitate to reach back out.  We'd be glad to assist!