change keyboard modifiers on mac

Finally changing keyboard modifiers works on my mac!
This is very important for a mac connecting a windows keyboard,
since we need to switch command (win) key and alt key (option)
in order to make it work like a mac keyboard.

But this failed so hard sometimes and I have no idea why.

Finally I carefully read this:

Changing modifier keys in keyboard preference pane has no effect

It might be either Apple's bug or Logitech's bug, anyway,
what I need to do here is unplug my logitech mouse and then
reconfigure the keyboard, and it would work! Then I can
plug back the mouse, the keyboard configuration would still
be under effect.

The only problem left is that......
I picked the wrong keyboard :(
I don't want a big enter key, I want US layout... :(
I shall be more careful when picking this up :(

Otherwise it looks great. No picture though, sorry!
Maybe later if I get some camera.

It's a black keyboard with white caps and
cherry's soft tactile switches.
The white caps do not have printed words but carved words.