Solution
The ability to change the data representation is different for the different result processors:
STDF: The STDF standard dictates the numeric representation used to store data values in the STDF file. When viewing the file using an STDF viewer, the display formats for the result, low limit and high limit are defined by the C_RESFMT, C_LLMFMT and C_HLMFMT fields in the PTR. STDF viewers can choose to use those fields to format the data. TSM does not set those fields.
Debug Test Results Log: For TSM test steps, you can set the numeric format using the Test Numeric Display Format field in the Options tab of the step. The TSM Debug Test Results Log ignores the floating point numeric formats (e.g. those that contain %f, %g, etc.) but does honor other types of numeric formats (e.g. %u).
CSV Test Results Log: uses the numeric format "%$.15G" for all floating point numbers to match TestStand's default precision.