Currently, the customer label option in International version is unavailable. I'd suggest sending a feature request to our Product Engineers. This helps us determine what enhancements and improvements are needed to make our product more effective and convenient to use.
Here’s how:
Click the Gear icon.
Choose Feedback from the drop-down.
Type in your Comments, Suggestions or Feedbacks.
Choose Next.
Select a category, and click Send message.
Additionally, you can visit these articles that will guide you in customising sales forms in QuickBooks: