- Du hast ungespeicherte Nachrichten. — You have unsaved messages.
- Sie haben ungespeicherte Nachrichten. — You have unsaved messages.
Both occur, but often neither is used, because it’s usually possible to phrase a dialog or message in an impersonal way without becoming too distant, e.g. passive voice or man.
Namehat ungespeicherte Nachrichten. —Namehas unsaved messages.- Ich habe ungespeicherte Nachrichten. — I have unsaved messages.
- Es gibt ungespeicherte Nachrichten. — There are unsaved messages.
##ungespeicherte Nachrichten —##unsaved messages- ungespeicherte Nachrichten:
##— unsaved messages:## ##Nachrichten nicht gespeichert. —##messages not saved.##Nachrichten noch nicht gespeichert. —##messages not saved yet.##Nachrichten wurden noch nicht gespeichert. —##messages have not been saved yet.- Sollen alle Nachrichten gespeichert werden? — Should all messages be saved?
- Nachrichten speichern? — Save messages?
- Alle Nachrichten sollen gespeichert werden! — All messages should be saved!
- Alle Nachrichten speichern! — Save all messages!
- Speichere alle Nachrichten! — Save all messages!
Some of the examples above turn the original informative statement into an actionable option, dialog or command. Which one of these is most appropriate, depends a lot on the situation and local user interface guidelines, which may apply to other languages as well. That would be more on topic elsewhere, though.
Sometimes, e.g. in video games, the software has a persona and the user (or player) does, too. Their (simulated) social relationship determines the level of familiarity, respect and politeness, hence the appropriate pronoun. A lot of professional software nowadays does the tedious tasks a secretary or other underling would have done in earlier times, so the boss – even if low in human hierarchy – would probably expect respectful Sie. Other software may be seen more like a colleague, therefore could use friendly du.