when I make a copy of invoice,the mount will be changed to zero

We can perform some troubleshooting steps to help you sort out this issue, huaming.
 

When creating a copy of invoices in QuickBooks Desktop (QBDT), it should also copy the details and won't change the amount. 

We can use the Verify and Rebuild Data tool. This way, we'll be able to identify and resolve the most commonly known data issues. Ensure to create a backup company file first to secure your data in case you encounter problems. 

Follow these steps on how to verify data:

1. Go to File, then select Utilities.
2. Select Verify Data.
3. Then, go to File, Utilities, and then select Rebuild Data.
4. Choose Window, then Close All.
5. Go to the File menu, and then click Utilities.
6. Select Rebuild Data.
7. Follow the onscreen instructions to back up your data.
8. When the tool finishes, select OK.
9. Navigate to the File menu, then click Utilities.
10. Click Verify Data, then select Rebuild Now once QuickBooks finds an issue with your company file.

But if the persists, I suggest contacting our QuickBooks Desktop Support Team. They can access your account in a safe environment during a screen-sharing session to investigate your concern and give you a possible fix for this query.

For future reference, you can email sales forms, invoices, and statements to your customers by following the detailed steps in this article: Email sales forms, invoices, and statements in QuickBooks Desktop.

You can always keep in touch if you have any concerns about unpaid items or deposits. The Community is always here to help, huaming.