Capitalizing pronouns in Spanish is questionable. Pronouns, being I, you, he, she, it, we, you, and they, all depend on where they go in a sentence. If they are the first word, they will be capitalized. If not, the only one that would be capitalized would be the polite form of you, and they: Usted and Ustedes, with no regard to its place in the sentence. The informal terms for you and they, being tú and ellos/ellos, would not be capitalized anywhere except as the first word