Is there a way to save map layers to the 'default' on arcgis online?
Essentially when you login to an online account and click 'Map' right at the top it always comes up blank and then I need to go in and add each layer from a group. Is there a way to save layers to this so when I login and click map it just opens whatever layers I saved to it>
Opening Map Viewer from the app selector opens a "blank" map, similar to how opening Microsoft Excel will open a blank spreadsheet.
If you'd like to open the same set of layers every time, you can add those layers to a blank map and then save that map to your content. The next time you log into ArcGIS Online, instead of opening Map Viewer directly, you can open that specific map and you'll have the content you're looking for, at the ready.
Hope that's helpful!