Previewing templates is essential to see how the layout looks like, @jackselectrical. We can perform some troubleshooting to isolate this issue.
Before proceeding, I'd like to know if you encountered any error messages. What template are you using? Are you creating a new form or opening an existing one? Any additional information would help us narrow down the issue.
In the meantime, let's access your QuickBooks account via incognito or private window. This mode doesn't retain cache, so we can verify if it is a webpage issue. Here are the keyboard shortcuts you can use:
- For Firefox, press Ctrl + Shift + P
- For Chrome, press Ctrl + Shift + N
- For Safari, hold down Command + Shift + N
From there, choose a template to preview. If this works, clear the browser's cache to remove the built-up cache in your default browser and start with a clean slate. You can also use other supported browsers as alternatives.
Moreover, the Preview option is no longer available in the new invoice experience. As a workaround, you can either select Print and download right from the invoice screen or go to the Customer Form Style to preview the invoice template.

See this article for more tips about personalizing forms: Customize invoices, estimates, and sales receipts in QuickBooks Online.
I'm adding these resources to guide you in glancing at the sales status and monitoring inventory:
Please use the Reply section below for further concerns. I'd be pleased to assist you again. Stay safe.