How can I set the Y-axis range in Zedgraph?

I want to set the maximum and minimum values ​​of the axes. The following code is only valid for one Y axis. I want to set 3 Y axes.

graphPane1.YAxis.Scale.Min = 0;

graphPane1.YAxis.Scale.Max = 100;

      

        
        
        
      

    

Here are my codes:

var y1 = graphPane1.AddYAxis("YAxis-1");

var y2 = graphPane1.AddYAxis("YAxis-2");

var y3 = graphPane1.AddYAxis("YAxis-3");

LineItem myCurve1 = graphPane1.AddCurve(txtPlotTitle.Text, first_pointsList, Color.Blue, SymbolType.None);
myCurve.YAxisIndex = y1;

LineItem myCurve2 = graphPane1.AddCurve(txtPlotTitle.Text, second_pointsList, Color.Yellow, SymbolType.None);
myCurve.YAxisIndex = y2;

LineItem myCurve3 = graphPane1.AddCurve(txtPlotTitle.Text, third_pointsList, Color.Green, SymbolType.None);
myCurve.YAxisIndex = y3;

      

        
        
        
      

    

Edit: When I try to run this code, the program throws an error. Also I want the graphs to auto-scale when I am not writing anything in the text boxes. I've tried if loop for this, but it doesn't work.

var y1 = graphPane1.AddYAxis("YAxis-1");
var y2 = graphPane1.AddYAxis("YAxis-2");
var y3 = graphPane1.AddYAxis("YAxis-3");

LineItem myCurve1 = graphPane1.AddCurve(txtPlotTitle.Text, first_pointsList, Color.Blue, SymbolType.None);

myCurve.YAxisIndex = y1;         

graphPane1.YAxisList[y1].Scale.Min = double.Parse(textBox1.Text);
graphPane1.YAxisList[y1].Scale.Max = double.Parse(textBox2.Text);

LineItem myCurve2 = graphPane1.AddCurve(txtPlotTitle.Text, second_pointsList, Color.Yellow, SymbolType.None);

myCurve2.YAxisIndex = y2;
graphPane1.YAxisList[y2].Scale.Min = double.Parse(textBox3.Text);
graphPane1.YAxisList[y2].Scale.Max = double.Parse(textBox4.Text);

LineItem myCurve3 = graphPane1.AddCurve(txtPlotTitle.Text, third_pointsList, Color.Green, SymbolType.None);

myCurve3.YAxisIndex = y3;
graphPane1.YAxisList[y3].Scale.Min = double.Parse(textBox5.Text);
graphPane1.YAxisList[y3].Scale.Max = double.Parse(textBox6.Text);