The most common way people do it is to use .step if you are looking to change certain parameter(s) only. However, based on your exact description, you may look for something else, and may be you can consider using overlay in the waveform viewer.
Overlay can compare multiple .qraw data file from multiple simulation. By default, Qspice will delete this file when you close its corresponding schematic. Therefore, you have to manually copy and rename the .qraw file or disable auto-deletion of simulation data files in preferences. This is a simple procedure of two method of using overlay feature.
however, .step is a more common way to do it, except you are in a situation .step cannot do the job.
