No support in slicer

I seem to have a problem with the slicer software on my K8200 in that it doesn’t add any support material when printing. This means that if I were printing an empty cube for example, it would not be able to print the top because the filament would sag into the empty space beneath it.
I thought support material was supposed to be added automatically but it isn’t and there doesn’t appear to be any mention of it in the slicer program, or anywhere else for that matter.
The result is that printing anything with an ‘overhang’ of any sort is impossible.
Any suggestions would be greatly appreciated.

In the case of the cube you would want an “infill” you can find the settings in the slicer configuration.

For support you can turn it on in this tab.