If you have adjusted the graph by using the Shift-Y or
Scale-Y buttons, you may decide that you would like to reset the graph to the
default scale and position. This can be done for either a single pen, or
for all pens using the Reset Button. 
1. Decide whether to reset one pen or all pens
• If one pen, select that pen in the legend.
• If all pens, select no pens in the legend.
2. Click on the Reset button.