Can I modify the formatting of the charts created by Supermetrics Data Grabber?

Yes, the charts in the reports can be modified, and the modifications will remain when you refresh the reports. 

You can also modify the templates that Supermetrics Data Grabber uses to make the charts. These can be found in the Setting sheet (in older versions, these are in a hidden worksheet called "charttemplates"). Modifications done to these templates will appear in all new reports you create.