How to change the vertical axis scaling?

The y-axis scaling can be changed, e.g. from Linear to dB of plot type Time Data (Impulse Response).

If two plots are displayed, set the plot to which you want to change the scaling active by clicking in it (you will then see a small frame around it). Go to Plot->Plot Type Settings->Active Plot… to open the active plot type settings. Then in the upper part of the dialog box change the content of the Vertical axis list box shown below.