HOW TO CHANGE THE REFERENCE DATE OF A VARIABLE ?

1. Go to Data=> Variables.
2. Select your variable by clicking on the text.
3. Choose another Date/Time variable as a reference

It will change only the reference date for this variable in particular.
You can see it on the Graph Explorer, by clicking on 1 point on the Chart (here we choose DateTime+1h for this variable, the reference date of the entire Base is DateTime)