Trace 1, 2, 3 Select, Legend and Color
Traces that are not active (window not opened) are grayed and can't be selected. Active traces can be selected or unselected by clicking on the Trace 1, Trace 2, or Trace 3 check boxes.
When selected you can edit the legend that's used for that trace on the graph. The legend is usually the trace's name, but you can enter up to 50 characters here. The trace legend is saved as part of the trace, so if you want to save any changes you've made, you must save the trace after making the changes. The next time this trace is loaded the legend is also loaded. When you rename a trace the legend is automatically changed to the new name, so don't spend time entering legends until you've given the traces the names you want to save them by.
The color of each trace's legend and plot on the graph is controled by the Color combo box for each trace. Click on the Color combo box and select the color you want for that trace legend and plot.