Excel's "factory" default chart type is a two-dimensional clustered column chart—that is, a vertical bar chart in which series are plotted side by side along a single category axis. To make a different type of chart the default
Create a chart.
Select the chart, and choose Chart, Chart Type.
In the Chart Type dialog box, click Set As Default Chart.
If you find yourself using a particular combination of chart formatting settings again and again, add that chart to the Custom Types tab of the Chart Type dialog box, and then make your new custom type the default.