This icon set doesn't replace any existing icons; it adds new icons. To use it you have to edit individual buttons/menus to make them use the new icons.
Hi Leo. Yes, I understood that this nice icon set is an addition, not a replacement (after all they are only 44 icons). The point is that I've ried to edit some of the buttons I've created to launch some of the apps I use most frequently (you'll remember also the MP3Tag one you so kindly made for us), but I really can't find a way to replace some less than stellar icons (the Move To and Copy To in particular which look quite pedestrian).
I'll do some more investigating on this. However it would seem that the replacement of one button by another should be fairly simple, but you know already that I have a "gift" to ignore the obvious.