I can see how important it is to run your business seamlessly, @rachs26.
I admire you for sharing the details you've done to fix this. Let me direct you to the best support available so this gets sorted out.
I recommend contacting our support team. This way, one of our agents can look into your account and investigate why there's a letter T when viewing and printing your invoice. To reach to them, you can refer to the steps shared by my colleague AlexV above.
In the meantime, you can download our QuickBooks Online (QBO) Mobile App and view your invoices from there. Feel free to check out these articles for guidance in downloading the app and learning your ways around it:
In case you need to print your invoice from your QBO app, you can print them using a Bluetooth printer. If you don't have one, you can send the invoice to your email address and print it from there.
Moreover, I've added this link that you can utilize in personalizing your invoice base on your preference: Customize invoices, estimates, and sales receipts in QuickBooks Online.
You always have my attention whenever you need further assistance printing and managing your invoices. It's always my pleasure to help you. Take care, and always stay safe!
