The values in a chart are linked to the worksheet from which the chart is created. When you change one, the other is also changed.
Change values directly in worksheet cells
Change values by dragging data markers in the chart
To change values generated from worksheet formulas in 2-D column, bar, pie, doughnut, line, xy (scatter), and bubble charts, drag the data marker in the chart and use goal seeking. When you change the value of a data marker by dragging, Microsoft Excel also changes the underlying value on the worksheet.
To change values generated from worksheet formulas in 3-D, surface, radar, and area charts, use goal seeking on the worksheet.
If the data marker is a bar or column data marker, drag the top-center selection handle.
If the data marker is a pie or doughnut chart data marker, drag the largest selection handle on the outer edge of the data marker.
Note If the value of the data marker was generated from a formula, the value can be changed only by adjusting one of the values that the formula refers to. To accomplish this, the Goal Seek dialog box is displayed after you drag the data marker. Click the worksheet cell that contains the formula value you want to adjust, and then click OK in the Goal Seek dialog box.