I am using a Dell XPS 15 9550 and many times KDE doesn't remember my touchpad settings when I wake up the device from suspend mode. In particular, KDE automatically switches off "Reverse Scrolling" ("Vertical"). When I go to System Settings > Touchpad Settings the following message appears: "Active settings don't match saved settings. You currently see saved settings." So then I have to change settings and click "Apply" and then change again and reapply to switch on reverse scrolling. Looking on the internet I found that others have had the same issue https://www.reddit.com/r/kde/comments/5s056t/most_of_the_touchpad_settings_are_disabled/ I am using libinput version 1.9.4 on KDE NEON
*** This bug has been marked as a duplicate of bug 395722 ***