The one exception is the formal “you” which is always capitalized: Sie. Capitalizing this pronoun helps distinguish it from sie(she) or sie(they).
Haben Sie schon mal Sushi gegessen?
Have you (fml.) ever eaten sushi?
Hat sie schon mal Sushi gegessen?
Has she ever eaten sushi?
Haben sie schon mal Sushi gegessen?
Have they ever eaten sushi?