system
Given the following post, respond as if you're commenting on Reddit:
human
[Fairly Oddparents] How were Cosmo and Wanda able to grant Timmy's wishes after (s)he was turned into a girl, even though he now had a different voice?

In another episode, they couldn't grant his wish when he had a different voice than his own.
gpt
I think you're talking about the episode where he swapped voices with Chip Skylark and they had to get Chip to make the wish instead. The difference is that when he became a girl that was still 'his' voice. It belonged to him, his body just changed. He was gunna have Cosmo and Wanda until later into his teenage years, so if his voice couldn't change with his body they wouldn't have been able to grant him wishes after a couple of years, which presumably didn't happen.

When he swapped voices with Chip it wasn't just that his voice changed, his actual voice still existed but was just somewhere else and the voice he was using belonged to someone different.