The plot window has four menus: File, Display, Graphics and Operations.
You can turn off the display of error bars for this plot using the Display=>Error Bars toggle. If your data is in magnitudes you can flip the y-axis display so that your data is displayed the correct way up using the Display=>Magnitudes toggle. This toggle will propogate through any analysis you do to the data, such as detrending, fitting or folding.
Additionally the Display menu gives us basic control over plot window, allowing us to change the line style and how the plot is scaled in the window.
FROG - A Time Series Analysis Package