Hi KrisMc,

Appreciate you trying out the basic trouble shooting steps. Furthermore, you can also customise your sales forms by going to your Custom form styles. Here's how:

1. Click on the Settings icon or the Cog wheel Icon.
2. Click on Custom form styles.
3. Click on Edit for your Default template.
4. Under Content and Design tab you can make the changes you wanted for your sales form.
5. Click on Done.

You can then open one of your invoices and print/preview them to see how your sales form shows up.

Also you can check this link to learn more about: Customise invoices, quotes, and sales receipts in QuickBooks Online.

Feel free to post your concerns in the Community or click the Reply button for follow-up questions. We'll be happy to help. Have a good day!