The color of a selection is controlled by the operating system. E.g., enter the following code in separate cells.
nb=EvaluationNotebook SelectionMove[nb, Next, CellContents] 2+2
and the 2+2 will be selected and highlighted. One gets the same color highlighting text or input using the Mouse.
Is there a way to over-rule the OS and change the selection color using the Option Inspector...? I've searched for likely terms in the Option Inspector..., such as "Selection" and "Highlight", without success.