If you have not already done so, insert a chart by selecting it from the Insert menu, or double-click an existing chart to access the chart's configuration panel.
Select the General tab.
For each type of line (Control lines, Central Line, Warning Line 1, and Warning Line 2), select the Display Line check box to display the line, or clear the check box to hide the line.
For each type of line, click the Color button to choose a new color.
For each type of line, select a line width from the Line Width list box. If you do not want the line to appear on the chart, clear the Display Line check box.
For each type of line, select a line style (e.g., Solid, Dash Dash) from the Line Style list box.