To the left of each graph is a two-button control. The left-most looks like a magnifying glass. It is used to zoom-in and zoom-out the corresponding graph. To use it, simply press the button, and choose one of the following zoom functions:

After choosing the function, the cursor changes to a magnifying glass. Click and drag on the graph to apply the required zoom.

Keep in mind that each graph has a separate zoom and pan function. Select the proper function for the particular graph you are interested in before applying it. Make sure that the cursor changes to the proper function when the mouse is hovered on top of the graph.

Note that all three graphs are always synchronized along the X scale. Whatever zoom is applied to the X-scale over one graph is always applied to the other two. This way the X-scale is always the same for the three graphs.