Map size.
Make the map larger, the hills will automatically get smoother in most cases. Also play around with a height that's not too much.
If you want really smooth hills on a smaller map you should make a big mapsize and use boundaries I'd say.
However, in general you should use some sort of blurtool on the heightmap to get the smoothness of hill etc. The values in the map maker doesn't do it as well, but on a greater scale the change the appearance of the hills.