Note: This worked all right in Kubuntu 18.04 LTS.
I am using a fresh install of Kubuntu 18.10, with the default plasma version that comes with it: 5.13.5.
The option in System Settings keeps getting reverted every few minutes. On visiting again, it shows a message meaning that the "Options visible are different from those in effect" and on refreshing, option gets unchecked. Screenshot:
xinput --set-button-map 13 1 2 3 5 4 6 7,found in some answers is causing unreliable effect, i.e. some of the apps start working reverse while some work inverted of inverted (i.e. original default).
Is there a reliable, permanent method of setting "natural scrolling" in Kubuntu 18.10?
Update 1: I have seen that some of the options like X config work on boot, but at some point stop working randomly. I have not been able to pinpoint what causes it though (yet).
Update 2: Confirming that my natural scrolling option keeps getting reverted!