Solution
If you want an XY Graph to behave as an XY Chart by storing previous values, you must implement this behaviour programmatically.
The best way to do this is to build an array of the values, and in each iteration add the new value to the array. This array will store the values from all previous iterations in the shift registers, so they can be displayed on the chart on the next iteration. An example can be seen below:
Note: This image is a LabVIEW snippet, which includes LabVIEW code that you can reuse in your project. To use a snippet, right-click the image, save it to your computer, and drag the file onto your LabVIEW diagram.