To change the look of data symbols for only one data series, tap , then tap Chart.
Do any of the following:
Change the grid shape: Use the options below Grid Shape to choose whether you want the grid to be straight or curved.
Change the fill and stroke: Use the options below Style to choose whether you want all series to have a color fill, a stroke along the edge, or both.
If you can’t edit a chart, you may need to Use chart styles in Pages on iPad