EXFO FTB -5240S/5240BP Optical Spectrum Analyzer for FTB 500 (NS-1434) - Manual (Page 90)

Setting Up the Instrument in WDM Mode
82 FTB-5240S/5240BP
Setting Up WDM Analysis Parameters
6. Press OK to return to the Channels tab, which now contains the
modified settings.
7. If you want to apply the above settings to the active trace, select the
Apply to active trace and re-analyze option in the Channels window
and press OK.
8. Press OK to save the changes and close the window, or press Cancel to
exit without saving.