There is a cash shop item available in The Emporium to reset your Kill-Death Ratio (KDR).
Within the "Shop" section of The Emporium, search for the item, "Player Record Reset." This will reset will reset your kills and deaths total to zero(0) and will be final once you have confirmed it.
Once the process has been completed, it cannot be reversed or refunded at any time afterward.
You must be at least 18 years old to turn on the blood setting in Combat Arms. If you are younger than 18, the option will not be available to you.
It is possible that your firing key might be unassigned.
While in Combat Arms, click on the “Options” button and select the “Control” tab.
In the “Combat” section, make sure that Fire has a key assigned to it.
It is set to "LMB" or Left Mouse Button by default.
The drivers installed for your video hardware are likely out of date.
Confirm the manufacture of your video card and access their website to download the latest video card drivers.
Here are links to some of the common providers of video cards/video chipsets.
AMD/Radeon (Catalyst Drivers)
The links provided are from the US sites and may be different depending on your region.