Having issues with income accounts on Chart of Accounts linking to Sales Receipts. It wants me to add new accounts instead of picking up existing ones. How to resolve?

Welcome to the Community, @borokmoss.

When creating a sales receipts, you'll have to add the products or services (linked to an income account) not the income account itself. If you wish to use the existing income accounts, you can associate it with the products or services, then process sales receipts.

Here's how: 

1. Go to Sales on the left panel.
2. In the Products and Services page, click on the New button.
3. Choose the type of product.
4. Fill in the fields.
5. In the Income account drop-down, select the appropriate account.
6. Click Save and close.

Once done, you can now add the item in the sales receipt:

1. Go to the +New button.
2. Choose Sales receipt under Customers.
3. In the Sales receipt page, fill in the necessary information and choose the product you created. 
4. Once finished, click Save.

I've added this resource to guide you in adding inventory products in QuickBooks Online: How to create and use a products and services list.

Please let me know if you have other QuickBooks-related concerns. I'm always here to assist you. Have a pleasant day.