You can flexibly add a line of auxiliary data, add the value pointed by the arrow at the time point when the arrow is needed, and leave the rest blank. Then, add this line of auxiliary data to the chart, change the chart type to a disconnected line chart (that is, only data points), draw an arrow with optional graphics, set the color and size, then copy the arrow and click the auxiliary data series you just added. Press CTRL-V to paste the arrow graphic you just copied as the marker of the data series. In this way, arrows and labels will replace the original default data labels of points or squares, and will change with the changes of data in auxiliary data rows. You can set a formula to automatically determine the time point of opening and closing positions, and return the arrow value to be marked at the corresponding time point.