Thanks for reaching out to the Community, LeesaMobile.
I can certainly understand how an ability to turn off warning messages about serial numbers while creating invoicves could be useful and have submitted a suggestion about it as of today.
You can also submit your own feature requests while signed in.
Here's how:
- In the top menu bar, go to Help, Send Feedback Online, then Product Suggestion....

- Choose a Type of Feedback and Product Area (optional) from your available drop-down menus.

- Enter any suggestions/feedback in the Here is my suggestion: field.

- If you'd like, include your name/email in the My name is: (optional) and My e-mail address is: (optional) fields.

- Select Send Feedback.

Your feedback's definitely valuable to Intuit. It will be reviewed by our Product Development team and considered in future updates. You can stay up-to-date with the latest news about your product by reviewing Intuit's Product Updates webpage.
As a workaround, you can dismiss when when they display for you.
Please don't hesitate to send a reply if there's any additional questions. Have a great Thursday!