How do I manually move the point on a graph so it changes the values on the formula that created it?

After you create a chart, you can change the data series in two ways:
Use the Select Data Source dialog box to edit the data in your series or rearrange them on your chart.
Use chart filters to show or hide data in your chart.
Edit or rearrange a series
Right-click your chart, and then choose Select Data.
Select Data Source dialog box
In the Legend Entries (Series) box, click the series you want to change.
Click Edit, make your changes, and click OK.
Changes you make may break links to the source data on the worksheet.
To rearrange a series, select it, and then click Move Up Move Up button or Move Down Move Down button .
You can also add a data series or remove them in this dialog box by clicking Add or Remove. Removing a data series deletes it from the chart—you can’t use chart filters to show it again.
If you want to rename a data series, see Rename a data series.
Filter data in your chart
Let’s start with chart filters.
Click anywhere in your chart.
Click the Chart Filters button Chart Filters button next to the chart.
On the Values tab, check or uncheck the series or categories you want to show or hide.
Values tab in the Chart Filters gallery
Click Apply.
If you want to edit or rearrange the data in your series, click Select Data.

I suppose you mean filtering the line chart so that the changes occurs on the Pivot Table.

If that's what you mean, you need to create a PivotChart from a PivotTable. On the chart, you will see filter buttons that allows you to filter the chart and the changes impact the PivotTable.