How do I stop Mojave Dark Mode turning itself on I recently updated to macOS Mojave and, although I think the Dark Mode is cool and has its place, it frustrates me no end that it seems to be on some kind of schedule. It turns itself on every day at 19:30 and I have no idea why, or how to turn this feature off.

Why is this setting activated and how do I change or edit this?
There's no scheduling available for Dark Mode at all. Perhaps you're thinking of Night Shift, found in System Preferences > Displays, which changes the color of the monitor to display warmer colors, which are better at night to minimize the effect of blue light on the production of melatonin.