Is there a restriction on what modifications you can make to a invoice template , Estimate Template ? I currently have a Quickbook Plus Subcription

Yes, bruce6. There's a restriction on what you can modify as QuickBooks templates are pre-designed to meet your business needs.

Since you have a QuickBooks Plus subscription, you can customize invoice and estimate templates by modifying layouts, adding logos, changing fonts/colors, customizing headers/footers, renaming field labels, adding up to three custom fields, reordering columns, and adding messages or attachments in your template.

If you require more advanced customization, you need to utilize third-party tools or manually import your invoice and estimate templates into QuickBooks. To better guide you in personalizing your sales forms, open this link: Customize invoices, estimates, and sales receipts in QuickBooks Online.

Stay in touch if you have other template concerns or questions about navigating through QBO. I'll be more than happy to lend a helping hand.