Time sync and .vbox file

[treeev]

I have instaled latest version VB (on windows . Follow the instruction:
VBoxManage SetExtraData “YOURVMNAME” “VBoxInternal/Devices/VMMDev/0/Config/GetHostTimeDisabled” “1″
i (as admin) I sucessfully do this command - and after start VB this line
<ExtraDataItem name="VBoxInternal/Devices/VMMDev/0/Config/GetHostTimeDisabled" value="1"/>
in config file (name.vbox) dissaper
I'ts look like VB setting override this file.