If your chart has negative values, then PowerPoint by default uses the same fill color for negative values in any chart. You can override this nature with the Invert if Negative option.
To learn more, choose your version of PowerPoint. If we do not have a tutorial for your version of PowerPoint, explore the version closest to the one you use.
Microsoft Windows
Using the Invert if Negative Option for Charts in PowerPoint 2013
Using the Invert if Negative Option for Charts in PowerPoint 2007 and 2010
Using the Invert if Negative Option for Charts in PowerPoint 2002 and 2003
Apple Mac
Using the Invert if Negative Option for Charts in PowerPoint 2011
Tutorial Code: 10 12 02
Previous: 10 12 01 Adjust the Chart Gap Width in PowerPoint
Next: 10 12 03 Changing Color for Negative Data Series of Charts in PowerPoint