You can do this right-clicking on any chart window   →    Chart settings   →   Color Scheme tab. You will have plenty of different options to change the look of the chart.

By the way, you can create a custom template and make it default for all the charts. 

Make all necessary changes in the Color Scheme and Chart settings tabs, apply the changes. Then save these changes as a template:

1. Right click the chart window > Templates > Save template
2. Give the following name to the template: default
3. Click Save and overwrite the existing template.