This is what is causing the undesired effect you are describing. Unset that option and it should solve your problem, since keeping the playhead in the middle means that the timeline has to move instead of the playhead.
I figured out that I have to turn it on or off under different circumstances. However, Power Director doesn’t require me to constantly turn a setting that does this on or off and somehow, the timeline is much more well behaved.
I like OpenShot timeline, yet their software has a number of other bugs that make it not very usable.
I do like Shotcut a lot. I just want to point out some things that keep me from switching to Shotcut from PowerDirector. I would wait for the version when some of the problems that I describe would be fixed before I make this transition.
It is not on by default. You do not need to turn it on and off repeatedly. That might be a sign you have not learned how to scroll or slide the window. It is typically a one time user preference. The timeline is well behaved.