1. Add the value indicated by the arrow at the time point where the arrow is needed, and leave the rest blank.

2. Add this line of auxiliary data to the chart and change the chart type to a line chart without lines.

3. Draw a new arrow with optional graphics, set the color and size, then copy the arrow, click on the auxiliary data series you just added, and press CTRL-V to paste the arrow graphic you just copied as the mark of this data series.

4. In this way, arrows and comments replace the original default data markers of points or squares.