I recognize the need to edit your template, Kayleigh.
Let's ensure you'll be able to edit your template in QuickBooks Online (QBO).
To edit your template, you can simply go to the Custom form styles and find the template that you want to edit.
Here's how:
Go to the Gear icon at the upper right corner and select Custom form styles.
Find the template that you want to edit and select the Edit drop-down.
Go to the Design section and select your preferences.
You can also edit the Content and the Email section.
Once done, select Done.
An alternative way to edit the template is by clicking the small gear icon on the interface of your Invoice, Estimate, and Sales receipt and then customizing it as per your choice.