How do I edit an ArcGIS Pro layout file?

Discussion created by NathanDuncan on Nov 27, 2017
Latest reply on Nov 28, 2017 by Dan_Patterson

I need to make modifications to an existing layout file (PAGX). I can find help on how to create a layout and how to import a layout, but I cannot find anything that tells me how to edit a layout. Importing the layout file in to an existing map document doesn't provide any way of editing it as far as I can tell, so what do I need to do?