I still have troubles with these as well... 'jou' is just to emphasize, but we could use 'je' as well. We could not use 'jij' here because that is used as a subject not as an indirect subject. Hope this helps:
This should help!
im still a little bit confused on this, but ill try to explain it. Jou is like a object pronoun. In english, you wouldn't say i give "he" an apple, you would say "him" Also in english, we do not distinguish between object "you" and subject "you", but Dutch does. Always remember that "jou" is like "him", and "je" is like "he"