Thanks for joining the thread, @SAL2021.

Let me share insights on how customizing sales form affects your transactions in QuickBooks. 

Any customizations or changes you make to your invoice templates will apply to all existing and future transactions. This is why when you edit a form, it also updates your other invoices that use the same template. 

As a workaround, you can create another template for specific transactions. Then, make sure to select that when creating an invoice. You can follow the steps in this article to add a new template: Customize invoices, estimates, and sales receipts in QuickBooks Online.

Here's how to select a form style when creating a transaction:

1. From the Invoice window, click Customize. 
2. Choose the form you want to use and make sure it's marked as check.
    

Let me share these articles as well for additional resources and guidance: 

• Add, Customize, or Remove Logos on Sales Forms
• How to Add Custom Fields to Sales Forms and Purchase Orders

If you need help with other QuickBooks-related tasks, please let me know in your reply. I'll be happy to assist you again. Have a great day ahead!