This is not possible. The frequency unit of markers in the MCS is determined by the device type: kHz for NF devices, MHz for HF devices.

@mm_dev 

It's odd that I'm unable to at least selectively set the marker menu to Hz, kHz, MHz, when the unit scans in all THREE spectrums. For example, The software frequency settings menu is configured to choose between Hz, KHz, MHz and GHz. However, the software marker menu is configured with one choice (kHz). A simple software update would make the unit more user friendly. I don't see the need for a firmware update to the unit if it already scans in Hz, kHz, MHz. The software could easily do the emulation if configure correctly.  Strangely, I can set a marker line on a Hz position, but there is no marker menu option shown in Hz. Shows only in kHz.

The other larger issue is that I'm only able to set the marker lines in (Hz) with whole number frequency values. For example, a (Hz) whole Frequency value: 1,2,3,4,Hz etc.  Decibels 1.2, 1.3. 1.4 Hz, etc.. NOT possible. The unit will scan in Hz decibel readings. The software emulates results in Hz decibels readings, but I can't set the marker to a Hz decibel position.    This is very odd.  Is this a unit limitation, bug or user error ?

My overall satisfaction level is 2.7 Hz

@rfxx The frequency widgets in the Settings control are a lot more complex and wouldn't work well within the marker settings. And as you can specify three decimal digits there the limitation to kHz still allows you to enter (full) Hz values.

There is only limited support for fractional Hz values for display purposes, all controls and most of the UI only deals with full Hz values to avoid rounding problems. This applies to both the PC software and the device itself.