How should I pay for the ticket if I change from subway Line 3 to Subway Line 2 to go to GZ South?

Hello, I want to go to Guangzhou South Railway Station from Baiyun Airport. I have to go to subway line 3 directly from Baiyun Airport and then change train into Line 2 in Jiahewanggang Station, is that right? How should I pay for this? From Baiyun until Jiahewanggang or from Baiyun until Guangzhou South Railway Station directly? Thank you for the answer...