To create a custom snapshot, customize a standard report and create a snapshot of the customized report when you run the report.
Go to report> Report overview> select the report you want to customize then customize the report
After that on the result page in the right corner select the snapshot icon
Please note that a Snapshot can only be generated from a customized report. Therefore, if you wish to obtain a snapshot of a standard report, you must first save the standard report as a custom report.

Once we click on the Snapshot icon it is directed to a “Customize Report Snapshot” page.
We can add the name of the Snapshot in the field Portlet Title
Check on the boxes of Narrow Portlet and Wide Portlet on the subtab of the List
In the subtab Graph, we can select the X-Axis and Y-Axis then save

This snapshot is now available for you to add to a dashboard portlet.