There is no simple or direct answer, which may be why you see no relevant
information in help for this.
If you want the current drawing to use a different default font when new
shapes are drawn, click anywhere on the page (to deselect all shapes) and
then set the font. Any future shapes drawn using the Drawing Tools will
have this font applied.
If you want future documents to use this font, you should save your document
as a template and use that to start your drawings.
If you want shapes that you drag and drop onto the page to use a different
font, you typically must edit the Text Style they currently have applied.
Select the shape and choose Format > Style to find out what text style is
applied. Then choose Format > Define Styles and edit that style to change
its font. Not every shape makes use of styles however.
--
Mark Nelson
Office Graphics - Visio
Microsoft Corporation
This posting is provided "AS IS" with no warranties, and confers no rights.