Before you start your own experiments, perhaps you should try this:
To view the orbits with the default values, click on Play and observe how the four Suns orbit in ellipses.
This is how you change the default values. Click on Pause and then on Reset. By way of an example, to change the velocity of the red body, hold the mouse cursor over the second velocity field (total fourteenth field from the top) that displays the value -1.0E4 in red. The label reads "Vely0". This is the y component of the velocity of the red body. Click into the field and change it to -2.85E4. The background color of the field changes to yellow while you are editing the number. Hit Enter when finished. The background color changes back to white to indicate that the edit is finished. Change the x component of the velocity of the black body also to -2.85E4. Then change the y component of the velocity of the blue body to 2.85E4 and the x component of the velocity of the green body to the same value. Thus all bodies have the same speed 28500.0 m/sec (but in respectively different directions). Click on Play and observe the bodies chasing one another in a perfect circle.
When making other experiments with the model, always remember to Pause and Reset before changing any defaults.