When you change a dimensioning system variable, you are actually setting a document override for the active dimension style; you are not changing the active dimension style itself. This means that all newly created dimensions will still be created with the active dimension style only and will not reflect the overrides from the system variables. The overrides from the system variables will not be recognized on new dimensions until the active dimension style is updated. To change the settings of any dimension style, use the CopyFrom method. This method copies a dimension style configuration, including overrides, from a document, dimension, or other dimension style.