Main toolbar > Select and Uniform Scale (on Select and Scale flyout)
Right-click an object. > Scale (selects current toolbar Scale mode)
Uniform scale does not change an object's proportions
The Select and Uniform Scale button, available from the Select and Scale flyout, lets you scale objects by the same amount along all three axes, maintaining the object's original proportions.
To scale a single object, you don't need to select it first. When this tool is active, clicking an object selects it and dragging the mouse scales it.