Let me discuss a few details of why the link doesn't work, @Wilcomm.

The feature to import custom invoices in QuickBooks Online is no longer supported. As a result, you won't be able to access the link shared in the previous post. Nevertheless, there are still ways to customise your invoices within QuickBooks Online, such as using the available custom form styles or designing your own form style. I'll walk you through how:

Important: Keep in mind that any customisations you make on your invoices or quotes will apply to all existing and future invoices and quotes. And any edits to your company info will update your company info everywhere in QuickBooks.

Using the new layout:

1. Go to Get paid & pay or Sales, then hit Invoices.
2. Select Create invoice to create a new invoice. Or, to edit an existing one, find the invoice from the list and click on View/Edit from the dropdown ▼ under the Action column.
3. To update your company info, tap Edit company on the form. Make changes as needed, and then tick Save.
4. To edit your company logo, select the logo on the form. Then choose an image from your computer, and Open to update the logo.
5. To add or remove fields, change the colour scheme, or turn on payments on invoices, tap Manage ⚙, if not selected already.
6. From the dropdown ▼ for each section to see customisation options.
7. Pick what info displays on your form by turning the switches on or off. The form preview updates as you make changes.
8. Click on Payment options or Discounts and Fees to customise payment options, or turn them off.
   Note: Payment processing is an add-on service.
9. Optionally, in case of invoices, select Automation to set up a Recurring invoice.
   Note: This option takes you to the recurring invoice form.
10. Once finished, hit Save.

Using the old layout:

1. Go to Settings ⚙ and then select Custom form styles.                                                                                                     
2. Select New style.                                                                                                                                                             
3. Select a sales form type you’d like to create a template for.                                                                                       

After that, kindly follow Steps 2 to 7 from this article for you to completely personalise your invoices: Customise invoices, quotes, and sales receipts in QuickBooks Online.

Moreover, you can look for a third-party importer tool that you can integrate with QBO so you can get the functionality you desire.

Finally, I'm adding this extra guide on how you can record your customers' payments in QBO.

You can always get back to us if you need more help handling invoices or QuickBooks. I'll be around to assist. Stay safe and healthy!