For a single topic or a selected group of topics:
The quick way
- Select the topic and press Ctrl+Space
To just reset the Font or the Topic Formatting
- Right click it
- Font or Topic Format
- Map Theme
- Revert to Default Theme (or Style).
If you want every topic to be reset to default:
- Expand your map to show all branches
- Hit Ctrl+A to select all
- Hit Ctrl+Space.
This will reset all topic formats and fonts to their default settings.