Why does Apollo want phaethon to change his request?

Apollo encourages Phaethon to change his request because he fears for his son's safety. Phaethon wishes to drive the sun chariot, a task that is perilous and beyond his abilities, risking both his life and the stability of the world. Apollo understands the dangers involved and wants to protect him from the disastrous consequences of such a reckless desire. Ultimately, he hopes to steer Phaethon toward a safer, more reasonable request.