It would be great if the data model viewer could have an option to save the manually-created layout. Perhaps its just the version I'm on (Nov 2020 Patch 6 13.102.13) but even if I lock the layout, it still gets lost when I close the tab. It seems to always revert back to the layout I created many moons ago.
Before this was an issue, I've also noticed that, if I load an app with the data of one customer (customer A), and set a layout, and then reload the same app but with data from another customer (customer B), the layout is lost.
When I load customer A's data again, my layout is back the way it should be. The layout, therefore, seems to be linked to the content, not only the app.