Welcome to the Community, @stuc.

You can upgrade to an expensive subscription, but it doesn't guarantee that you can continue to use the old invoice layout you're used to.

If you still have the option to switch back to the old invoice layout, you can use it. Please note that by changing back, you may be unable to utilize and use the new invoice layout.

When a customer pays, we must record the payment and link it to the invoice for accounting purposes. For more information, please refer to this article: Record invoice payments in QuickBooks Online.

If you have other questions regarding invoices, feel free to comment below. The Community is always here to help you.