When you select Edit GAD Objects and click the Edit… button, the Edit GAD Objects dialog opens. In it, every single object in the structure is listed, with all geometrical properties.

Click on the Sphere... (or any other object type) button to open the corresponding widget and see all details:

The dialog gives the choice to Remove single objects altogether, to change the material ID assigned to any of them, as well as to modify their size, position, orientation, shape, etc.

At the bottom left, you can decide to limit the range of objects shown in the dialog by selecting the numbers and clicking Show Objects. At the upper left, click Reset to return the dialog to the original parameters of the listed objects.

When finished editing, click OK to return to the GadGeo section. There, click Run to apply the modifications to the current structure.

For example, observe the effect of increasing the Diameter of the red sphere from 20 to 40 µm in the matchstick structure.