In fact, the section layout shows the title beginning at position 4, where, I guess, the middle of the title should be – don’t know if this is significant. But I played around with this and found that the alignment option has no effect. For example, if I select left-justified, the title stays put. I don’t get it!
What you are overlooking is that your titles are centred based on a ruler with an indent. To get them properly centred you need to move the T-bar first line indent marker from its current position at 0.25" (partially masked by the Tab marker) back left to the margin at 0".
I find picking up that T-bar, rather than moving the Tab-marker or even creating a new Tab-marker, very fiddly.
Mark
P.S. And you might click Override Text and Notes Formatting if you want settings in this pane to be implemented!