You have in fact customized the trace names in your attached image. You are able to change a signal name by double-clicking on it in the PLECS Scope Data window list ("Am1" currently). However, if you save and name multiple traces of a signal, the signal name will be the same for all of them. You should use the trace names to differentiate the results. In your example, you have two traces of the same inductor current (measured by component "Am1", a name which you can change as I just mentioned), one with an input voltage of 5V and one with an input voltage of 10V. So the signal is the same, but the specific behavior of it can change with each trace. Let me know if anything isn't clear.