When you change the font in the Text dialog box or in the Text list on the Formatting toolbar, the new font is not applied to unselected shapes or to shapes that you subsequently place on the page.
Font changes that you make in the Text dialog box or in the Text list on the Formatting toolbar apply only to the text in shapes that are selected when you change the font.
Apply a Theme Effect to change the font for all shapes in a drawing — including shapes that you subsequently add.
Open the drawing in which you want to apply a default font for shapes.
If the Theme task pane isn't open, on the Format menu, click Theme.
If the Theme - Colors task pane opens instead of the Theme - Effects task pane, in the Theme Colors box, click Theme Effects.
In the Theme - Effects task pane, click New Theme Effects.
In the New Theme Effects dialog box, on the General tab, type a name for your theme.
Click the Text tab and, in the Font list, click the font that you want to use for all shapes in the drawing.
Click the Line, Fill, Shadow, and Connector tabs to adjust those options if you want to.
The new font is applied to all shapes on the current drawing page and your new theme effect appears under Custom in the Theme - Effects task pane.
Right-click your custom theme, and then click Apply to All Pages on the shortcut menu.
The new font is applied to all shapes in the drawing as well as to shapes that you subsequently place in the drawing.
Note: A custom theme is available only in the drawing in which you create it. To learn how to apply the same theme to other drawings, see Copy a custom theme to another drawing.