Use the radial button to select Arith (Arithmetic).

An arithmetic scale (sometimes called "linear") shows equal spacing between the chart units. Price is measured in equal price intervals which are automatically set by the number of gridlines chosen. It is often seen as preferable for shorter chart histories. (In the example pictured, one gridline each .05)

Use the radial button to select Log (Logarithmic).

A logarithmic scale shows an equal percentage difference between the chart units. Price is measured in equal percentages which are automatically set by the number of gridlines chosen. While the percentages remain the same between gridlines, the gridlines are not evenly spaced. It is often seen as preferable for longer chart histories. The standard log chart will have rounded numbers.

Use the check box to select Lock Between Symbols. Locking the log chart means that whatever value you choose to Lock your chart scale to, that value will be for every chart you view in this mode. Check or un-check Show SP-500 to show/hide a comparison plot plot of the SP-500

Log %Grid display mode. (Place a checkmark in the tick box to choose %Grid). Increase/decrease the number of gridlines and the percentage adjusts itself. Zooming to more or less price history or changing the time frame of the chart will affect the % shown. The %Grid log chart will not have rounded numbers. The percent difference between gridlines is shown in red at the bottom of the scale.

This scale method allows you to set the percent difference desired between gridlines and how many gridlines you want to see. (In the example below, there is 5% between the lines and 12 lines showing.) The percent change shows in red at the bottom of the scale. (This will need to be done in each timeframe you use.)