Steps to reproduce:

1. Go to fresh install Administration - Geographical maps.
2. Try to chnage Zoom level or or Tile URL or Attribution for pre-configured options

Result:

Expected:
Pre-configured options doesn't allow to modify something in case of a service chnage or if you need to chnage Zoom Level for example.
Custom option - it's only one, so you cannot add 2+ custom options even for pre-configured.