When I write an invoice I can see my account number, as soon as I email it over it’s starred out. Why is this happening?

I highly appreciate you bringing this up here in the Community forum, Dann. I understand how essential it is to have everything working correctly so you can focus on what you do best. No worries, I've got some valuable insights to share with you and provide an alternative way to make the account numbers visible.

QuickBooks automatically masks sensitive information (such as bank account numbers, credit card numbers, and social security numbers) in forms/ reports by default to help protect against unauthorized access or identity theft.

Moreover, this is a standard security feature in many accounting and financial software systems which helps to ensure that account numbers and other sensitive data are only viewable by authorized individuals who have a need to access them. 

If you want to show the account numbers, you can put them in the message to customer or in the memo/description field as an alternative. For visual reference, I've added a screenshot below:

Additionally, I'll be dropping this article you can browse through to unleash your creativity and personalise your invoice, sales receipt, or estimate template to match your unique style: Customise invoices, estimates, and sales receipts in QuickBooks.

Keeping your business running smoothly is my priority, and I'm committed to making sure you have all the support you need to succeed. If there are any other aspects of QuickBooks that you’re curious about or need help with, don’t hesitate to ask. Wishing you continued success and looking forward to assisting you further.