On hovering the mouse pointer over or near any band in the equalizer, the frequency represented by that band is shown along with the markings, allowing for more precise adjustments in terms of values.
Once you make a change in the equalizer settings by manually adjusting the frequencies, the preset selector changes to a section where you need to enter a new name for it. This gets added as a new custom preset. Custom presets can be selected or edited from the same drop-down list that shows the main Boom 3D presets.