Virtual memory range for PCH exceeded

Win7 16gb ram VS2013
Changing virtual memory to “system managed” didn’t solve the problem for me.
Can some1 explain how to change /Zm1000 to /Zm400?
I’ve found VCToolChain.cs in UnrealBuildTool>Windows.
According to microsoft
I change it in property pages but it’s inactive (grey key in properties) for VCToolChain.cs
I’m kinda new to this so basic explanation would be appriciated.