The Scale option lets you set the scale of the graph. By default, the graph will always zoom in to show the maximum level of detail to make it clearer to see the different cohorts on the graph. Users have the option to choose the scale of the graph.
It can be set to All, Zoomed, Zoomed from the Start or Custom. The Zoomed and Zoomed from the Start give the greatest detail. The Zoomed showing a level above the data range and a level below, the Zoomed from the start shows from P1(i) to a level above the data range. The custom option allows you to select the starting point and ending point on the Y axis of the graph.