@bugceg Reference this blog and video 'How to add watermark to ArcGIS Pro'
In Layout mode, you can add 'user' from the Dynamic Text tool
Thanks for your reply @AyanPalit . Could I make "dynamic text" private(hidden)? i.e. can I make only certain users see it?
The user dynamic text will update to the individual viewing the layout on their instance of ArcGIS Pro.