questions about upper and lower layers of the two curves , Qchart

[Flame]

I would like to konw how to set the upper and lower layers of the two curves or how to set the upper and lower overlays of the curves ,just like this picture

I wanna use the red vertical bar to cover part of blue curves,but sometimes unsuccessful。

[jsulm]

@flame said in questions about upper and lower layers of the two curves , Qchart:

sometimes unsuccessful

in what way?