Menu: Edit→Shape of Object
To change the size and shape of a variable (rectangle or ellipse), press . Then point to the variable, press the left mouse button and move the mouse. If you change the size and shape of a selected variable, the size and shape of other selected variables will also change.
To change the shape (curvature) of a double-headed arrow, press . Then point to the double-headed arrow, press the left mouse button and move the mouse. If you change the curvature of a selected double-headed arrow, the curvature of other selected double-headed arrows will change too.
See also: