Verify that you are on the Monthly Totals worksheet, and if necessary, select the Monthly Totals combo chart.
Save the chart as a template.
Right-click the chart and then select Save as Template.
In the Save Chart Template dialog box, ensure the Charts folder is selected.
Note: Excel should automatically direct you to the Charts folder. The label in the chart templates path image will be your user name. The AppData folder is typically a hidden system folder, so you will not see the folder when browsing through File Explorer. However, you can type %APPDATA% in the address path to go to that folder directly.
step_result_lsn04_tpcc_act02_01.png
In the File name field, type Trendline Chart Template
Verify that the Save as type is Chart Template Files(*.crtx), and then select Save.
Test the new chart template.
Select the 2021 Sales worksheet.
Select the range A1:C7.
Select the Insert→Recommended Charts dialog box launcher.
Select the All Charts tab, and select the Templates category.
In the My Templates section, select the Trendline Chart Template and select OK.
Verify that Excel created a dual-axis combo chart with a trendline.