EXFO FTB -5240S/5240BP Optical Spectrum Analyzer for FTB 500 (NS-1434) - Manual (Page 212)

Setting Up the Instrument in Spectral Transmittance Mode
204 FTB-5240S/5240BP
Setting Up Spectral Transmittance Analysis Parameters
4. If you want to apply the above settings to the active trace, select the
Apply to current measurement and re-analyze option and press OK.
5. Press OK to save the changes and close the window, or press Cancel to
exit without saving.
Press Restore Defaults to remove all the changes and apply the default
values.