Start the unit and use the preset scan and settings. Input a -10 dBm signal @ 100 MHz for tracking. Note in the first pic that I have a marker on the signal and have a display line set to the noise level at the beginning of the trace.
Go to Trace/PF button and select Trace Type > Video Avg. Note that the noise level goes down from ~-65 dBm to ~ -75 dBm at the start, and the noise level is averaged (as it should be). Also note now the signal level is incorrect, it now shows -21 dBm.
Now simply change back to the original trace setting - Clear/Write. Now note the trace did NOT go back to the original type of trace, and that the noise level did not return to the same level, and that the noise still seems to have some sort of averaging going on.
Remember, all I did was turn on the unit, put in a signal at 100 MHz @ -10 dBm, and change the trace type from Clear/Write to Video Avg and back again. Something else is being changed when you select Video averaging for the noise level to actually drop, and that something is not being changed back to what it was when you re-select Clear/Write. Also, in any case, the signal power level is now wrong.
Thoughts ...