Dear Joe Silva1,
Good morning! Thanks for posting in the Microsoft Community. We are happy to help you.
Based on your description, I understand your frustration with the inability to edit the subject line in Outlook. I'm sorry to hear that this feature is causing problems in your workflow.
Regarding the issue you are experiencing, Microsoft has made some changes to the way the subject line is handled in Outlook. In the latest versions of Outlook, including the New Outlook, the subject line is now considered a part of the message body and cannot be edited separately.
However, there are still ways to add project numbers or other information to your emails. One option is to use the categories feature in Outlook to label your emails with specific project numbers. Another option is to use the message body or the email's flagging feature to add project numbers or other information.
I hope this information helps. If you have any further questions or concerns, please let me know.