The situation:
After installing an update, PDF Annotator either...
The language setting under "Extras, Settings, Preferences, Language" (or "Extras, Settings, Voreinstellungen, Sprache") is unavailable (greyed out).
The solution:
A typical cause for this could be that your antivirus software has blocked access to, or quarantined parts of the PDF Annotator application.
Please follow these steps to reinstall PDF Annotator: