The station number is linked to the computer name of each station. If you need to change the name because, for example, you have moved computers for station 1.
To do this, go to administrator settings from the launcher, then to station management:
Select the station id you need to change, and hit edit hostname. You'll need to type in the computer name for that station, and you will absolutely need to make certain it is correct.
Additionally, do not leave the same hostname for two different station IDs; this can cause a number of issues, most notably an issue with station specific settings not loading properly each time.