Ubuntu tweak tool - Mouse cursor would not change theme

I tried to change the cursor theme from DMZ-White to DMZ-Black for my laptops. But it does not work for one of my laptop.

For that laptop, it does not work no matter I change the cursor theme in - Ubuntu tweak tool, - or changing it in gksu gedit /usr/share/icons/default/index.theme, - or changing it in sudo update-alternatives --config x-cursor-theme

What else can be done to change it? Thanks in advance!

==edit== sorry turns out that my mouse cursor is partially changed.... in the main content of firefox browser, the cursor is changed to black, however if the cursor is on the launcher / File/Edit/View bar, it is still white.

How come???

That is a known issue. To change your cursor globally follow below instruction.

Open terminal and paste gksu nautilus hit enter then insert your password hit enter.

You will be now viewing nautilus as root. now go to file system on left panel.

Navigate to /usr/share/icons/default and open index.theme with your favorite text editor and change DMZ-White to DMZ-Black.

Or you can apply this change easily by executing the below command

sudo sed -ri 's/DMZ-White/DMZ-Black/g' /usr/share/icons/default/index.theme

And it's done! Either Reboot your computer or run the command to see the changes

compiz --replace

you can use sudo update-alternatives --config x-cursor-theme

Then choose any theme you like..

to apply either restart or compiz --replace