The Store Latest Run option, accessed from the Experiment menu, saves the most recently collected data in memory allowing you to take another collection without losing the first one.
The Latest always contains the most recently collected data and is overwritten when you collect more data. When you Store the Latest Run, a new data set named Run1, Run 2, etc. is created and the values of the Latest data set are copied to it. Columns in the latest data set are drawn with thick lines on the graph, while other columns are drawn with thin lines.
Using Store Latest Run does not save data on disk, nor will it preserve your data between sessions or when you turn off your computer. You must select Save from the File menu to save all your data permanently.