You cannot set a controls default value wihle the VI is running. Doing this requires the VI to be recompiled, and that cannot be done while the VI is running.
The easiest way to do what you want would be to read the controls value as the VI shuts down and write it to a config file. Then when the VI starts up again, read the config file to get the last value and write it to the control. Check out the 'Config File' VIs in the File IO palette. These are made just for reading and writing to config files. Ed
