Hi there rob_bennetts-yah,
It's vital that all your transactions have the correct balance so that your books can be well balanced. QuickBooks Online is a great tool able to help you create and send invoices to your customers for the services you provide. I can provide some information about invoice customization.
The default templates within QuickBooks Online can't have the addresses be moved to other sections of the invoice. One way around this would be to design a custom form style in a DOCX file then upload it by going to the Gear Icon, then Custom form styles. Click on New, then Import. Here are some instructions on how to Import custom form styles for invoices or estimates.
I can see how being able to customize the location of certain fields in the default form styles in QuickBooks Online would be a feature that you'd like to see in order to ease the process of mailing invoices to customers. I recommend leaving your feedback in the system by clicking on the Gear Icon, then Feedback. The comments made in this section will be taken into consideration when designing new features for QuickBooks Online.
If you have any other questions, feel free to reach out here.
