While changing the font of a single word is of course possible (and many apps allow that), we deliberately removed this option in Notebooks for a simple reason: assigning arbitrary styles to elements makes it increasingly difficult to maintain formatted documents. Should you ever decide to switch document style, for example, elements with explicitly assigned styles do not automatically adopt the new style and need to be changed manually, something that becomes increasingly bothersome.

That is why we recommend the use of formats like titles, heading, formatted blocks, bold, italic, or options instead. These automatically adapt to a different style’s settings.

Can I Change the Font of a Single Word in a Formatted Document?