Hi Ereona,
It is now quite clear what you want to accomplish can you please elaborate. Following are some suggestions:
1. You can modify the pair of zoom axis where the zoom is applied by changing the horizontal and vertical axis id properties of the range selection object added to the chart:
chart.RangeSelections.Clear();
NRangeSelection rs = new NRangeSelection();
rs.VerticalAxisId = chart.Axis(StandardAxis.SecondaryY).AxisId;
chart.RangeSelections.Add(new NRangeSelection());
The above code for example creates a range selection that will zoom in the secondary y axis.
2. You cannot zoom two axes that show completely different information simultaneously because they'll have a different range.
Hope this helps - let us know if you meet any problems or have any questions.
Best Regards,
Nevron Support Team