From the help file [fonts, settings]:

To view and change default text properties:
Select Text Style Palette from the Text menu.

Double-click Default Text, then from the expanded list of text types, choose an option (e.g., Artistic Text).

Click Modify to view current settings for the selected text type.

Use the Text Style dialog to alter character, paragraph, and bullet/list properties.

To save all current defaults as global settings:
Select Save Default Settings from the Tools menu.

From the dialog, check options to update specific defaults globally:

Document and object defaults - saves current site settings (page size, orientation) and object settings (context toolbar settings).

Text styles - saves current text styles in the Text Style Palette.

Object styles - saves user-defined styles from Styles tab.

Table and calendar formats - saves custom formats saved in Table Formats dialog.

Click Save to confirm that you want new sites to use the checked object's defaults globally.