It's a pleasure to be able to work with you today, @brchomeservice,
Resizing the fonts for QuickBooks Self-Employed invoices is unavailable at the moment. To increase the size of the characters on the sales transaction, click on Ctrl and + (Windows and Chrome OS) and ⌘ and + (Mac).
We listen to every feedback we receive from valuable customers like you, as we want to ensure all users enjoy QuickBooks at its optimum. I'll personally submit a request to our developers to have the ability to customize invoices in QBSE. They deliver time-saving features for our products from assessments and thorough evaluations.
You may also want to check this article with the details on how to process invoices in the web and the mobuile app: Create an invoice in QuickBooks Self-Employed.
Please feel free to let me know if there's anything you need help with. I'll be glad to share further insights and assistance whenever you need one. Have a wonderful week!