Hi Rebecca, are you interested in making global changes to layer names and pop-ups for layers that are part of existing web maps, or to feature layer items in the Portal, or both? As you may know, layers can be configured in a web map and saved as individual items containing filters, symbology and pop-up configuration, as reusable layer items.
While it's not possible to do global edits to the information via the Portal website, it is possible via the ArcGIS API for Python. Here is a related sample that demonstrates how to update web maps that contain references to a deleted service.
