Chart format keeps going away, when a different filter is chosen

Question

I have Powerpivot data that has 1.38 million records. I have created pivot charts with 4 report filters. Chart has three data series as stacked area, while two other data series are formatted as line. There are times when I change the report filter to choose what I want to view the chart for, all the five data series become stacked area. Is there a setting in chart options to prevent this happening.

Thanks in advance...

PR