I wrote an article earlier this year covering the new AutoCAD 2015 "selectioneffect" system variable. The article can be found at at this address. At the time I really was not too keen on the change since I found it a lot easier to see the old dotted line selection.
AutoCAD 2016 has added an option to the new selection effect that has made me a convert to the new highlighting method, they have added another system variable which allows you to select the color of the selection effect. I guess I did not like the blue tint they offered in AutoCAD 2015 because I really find blue a hard color to see on a black modelspace background.
If you refer back to the original post, you must have "Hardware Acceleration" turned on for the selection effect to function. You can check if this is enabled by looking in the status bar near the right side.
The selection effect is turned on by default but just in case you need to turn it on, use the "selectioneffect" system variable. The system variable is now also located in the System Variable editor located on the Express Tools ribbon.
The editor and the command line system variable will be asking you for a color to use. You will need to know the AutoCAD color number. If you do not know them by heart, you can stop your editing and jump into the "Layer Properties" dialog, select a color in the layer list and you will see all the AutoCAD colors by number. I will be choosing "red" which is color number 1.
Typing the system variable name "selectioneffectcolor" and pressing Enter, I will enter "1" as the command prompt. You could do the same thing in the System Variables dialog box.