The first thing I would suggest is to not use local variables. Instead, use property nodes and read the value property. This saves memory.
But related to the question, I'm guessing that the values are just reset each time another user runs the VI. They go to the default value. I couldn't tell when you read them as nil (0?), but if it's always like that at the beginning of the VI's run, then they are just holding the default value of that control.
J.R. Allen