Hi there, @Shawn45.

I have other ways to insert a signature on your invoices. And that is to use an imported custom form style.

To do this, you would create a template through MS Word. Then, insert images including your signature from there. Before doing this, make sure the Import style feature is on. 

Here's how:

1. On your QuickBooks Online(QBO) account, click the Gear icon.
2. Choose QuickBooks labs. 
3. Scroll down, then toggle the Import Style feature to on.
4. Click Done. 

To guide you on how to import and design custom form styles for your invoices or estimates in QBO, I suggest checking this article: Import custom form styles for invoices or estimates.

If you need help making invoices for your customers after creating a template in the future, you can check this article for the steps: Create invoices in QuickBooks Online. 

Let me know if you have any other questions. I'll be around to assist you further. Have a good day.