In most cases, the computer manufacturer has already configured the system to use the maximum amount of graphics memory that is possible for your particular computer model. The maximum share memory for Intel® HD graphics 4000 is 1.7GB. Sometimes you can change these values through BIOS level.
Check with your computer manufacturer if there are tips on increasing the amount of graphics memory for your computer model.
If you are interested in additional information see graphics memory frequently asked questions:
In this case the shared memory capacity is a feature set by the computer manufacturer in the Video BIOS, as I mention sometimes you can change these parameters through BIOS level, if there are no options available in the BIOS then there are no options to change the parameters.