Hi BStowell32,
Thanks for your post.
For changing the ABN, you may refer to this help article, changing your business details. You will also need to update your ABN for the STP and you need to do this on your Payroll reporting window. You'll need to go to Payroll reporting> Company information on the top left-hand side of the window.
Additionally our article, Edit company information for Single Touch Payroll reporting has additional information and instructions.
Please do let me know if you have any further questions.
If my response has answered your enquiry, please click "Accept as Solution" to assist other users find this information.
Kind regards,
Shella