How do you change the value of an simple variable in a design table?

Hi All,

This seems like it should be pretty simple to change the value of a simple variable in a design table but I must be using the wrong syntax. I established a variable called "ScrewLoc1" and assigned it a value of 0.875". I would like to be able to change the value of this variable for different configurations (see the attached JPEGS). The value does not appear to change for me. Can anyone point me in the right direction? Thanks in advance....

SolidworksConfigurations design Tables