I've come to ensure you're able to customize your invoices the way you wanted, Hope22.

With QuickBooks Online, we can modify and add specific details or formats to your sales forms. You'll want to personalize them to achieve professional-looking invoices when sending them to your customers. To do this:

1. Go to the Gear icon and select Custom Form Styles. 
2. Select a default invoice template and click Edit or create a New Style. 
3. In the Content tab, click on the Table section (middle).
4. Under columns, uncheck other data and ensure to check the Product/Service and Amount checkbox.
5. Modify and add necessary information from it, then click Done to save.

Moreover, I understand the relevance of having the flat rate option when entering your invoices. As we assess this feature to improve our product features, I recommend sending this feedback personally to our product engineers. They'll consider having this option and include them in our future product enhancements.

Here's how to submit feedback:

1. Go to the Gear icon and select Feedback unde Profile.
2. Enter your feedback or suggestion.
3. Then, click Next to submit.

I'm also sharing this helpful reference to guide you in receiving customer payments: Record invoice payment.

Feel free to let us know if you have further questions or concerns about managing your invoices. We'll be more than happy to help you anytime. Have a good one!