Make sure you are in the Scene Creator and not the Model Creator

Select the double ended arrow on the editor toolbar. This will put your object into scale mode

Select the item you want to scale by clicking on it, or selecting it from the object tree

You will see three lines which represent the three axis that can be scaled. This widget will be at the pivot point of the object. If you can't see the widgets, click and drag to look around the scene until you can see it.

When you hover over one of the coloured squares it will turn yellow. This means it is active and you will be scaling the object on the selected squares axis only

When you hover closer to the centre all three lines and the white squares will turn yellow. This means all three axis are active and you will be scaling the object uniformly

Click and drag to scale the object .