When you add text in a PDF, by default Acrobat picks nearby font attributes for the new text. Similarly, when you edit existing text in a PDF and the font is not available on the system, by default the font fall-backs to a specific font in a particular script; for example, font fall-backs to Minion Pro in roman script fonts. This default behavior can lead to fonts with an inconsistent appearance in a PDF document. To make it consistent throughout all the PDFs, instead of using the default settings, you can choose a specific font for both Add Text and the fallback option in edit text features using the Font Options under the Content Editing preferences.

Note:
To restore the default behavior, select Let Acrobat choose in the drop-down list.