Hello,
You can change the file format of the waveform by going into the File Details page of the Save Waveform menu. On the side of this page, you will see the options for .isf or ,csv. Push the button next to .csv so it is highlighted and then push the button next to OK Save. To convert your .isf files into .csv files, you can recall them using the Recall Waveform menu and then re-save them.