Right-click the Y-axis to open the context menu.
Show Single Y-Axis: Show the value range for one tag at a time. The range shown is for the tag selected in the Tag Info Grid.
Show All Y-Axis: Show values ranges for all tags. Though this takes up more screen real estate, it is more useful for printing and screen shots.
Common Axis: Force all tags to use the same value range while still fitting all values within the plot area.
Reset: Reset the Y-axis to its initial state.