Fixed HDD size

Hi, I have a question with VMware virtual machine setting.

I didn't set the virtual machine so I'm not sure why this is happened.

I really need to increase  the HDD's size at the virtual machine. However, i can't increase or decrease the size.

Can't even touch the number or up/down arrows.

This is the configure screen and the problem is at the red box.

Image may be NSFW.
Clik here to view.