"He managed to change."
Translation:Dia berhasil berubah.
Hai teman! The Indonesian pronoun "ia" is grammatically correct here. It is corresponding to the human or living being / thing / subject that is being discussed. And this cannot be used as a possessive pronoun, or an object pronoun. Instead, the forms used are "dia" (for humans, singular) / "itu" / "ini" (for things / living beings, singular and plural) / "-nya" (for humans, singular, for things / living beings, singular and plural), while the plural third person pronoun (subject pronoun) only for humans is "mereka", and the possessive pronoun or object pronoun is also "mereka" or "-nya".
I hope it helps.
Selamat belajar! :)