If you want to turn it on (or off) in the project setting, you have to go to:
Configuration Properties -> C/C++ -> Command Line
and then under Additional Options you can enter:
/w3####
to set your warning to level 3, and thus enable it; or you can enter /wd####
to disable a warning.
Current (2015,2017,2019,…) Visual Studio Versions also have a dedicated setting to disable warnings under:
Configuration Properties -> C/C++ -> Advanced : Disable Specific Warnings
… is equivalent to /wd####
.
Also useful in recent versions: C/C++ -> All Options
and then filter for e.g. “warn”.
It would appear that enabling รก la /w3####
is not yet exposed explicitly.