First off you might want to set your location.
If you are feeding FA, that’s done on your stats page.
Might not take effect until you restart piaware and dump1090-fa or just do sudo reboot.
In regards to range, a view of the horizon doesn’t mean all that much.
If the horizon is a hill, then you don’t really see the horizon 
Well technically it’s the horizon i think but … you get the picture, you can’t look straight, but only slightly up.
Check this page in regards to the possible range you can get: