It can be very useful to be able to substitute one or more shapes in a Visio diagram with a different shape.
These utilities can help you with that.
Select the shape (or type of shape) that you wish to replace. Select Shape → Shape Substitute from the ribbon.
The Shape(s) to Replace box will show options of which shapes to replace and the Replacement Scope boxes will allow you to change where the shape substitution will take place.
Choose the shape that you wish to be the replacement shape from the New Shape box. This will list all the shapes in all the open stencils.