I appreciate for sharing your screenshot with us, Kennedy. I can see that the default option to choose your preferred subject line is available, but it still prompts you to use the new one. Regarding this, we are going to send feedback about it.

By sending feedback, our product engineers will check this issue to understand why this is happening. Our team continually works to improve our product and enhance the experience for customers like you.

Here’s how to send feedback on the Invoice page:

1. Go to the Invoice page.
2. In the upper right corner, click on "Feedback."
3. Write your feedback, then click "Submit."

To receive invoice payments from your customers, check out this article: Record invoice payments.

If you need further assistance with managing your sales forms, just click the reply button. I'm always here to help.