@SuperRobotSolo
I think it's just based on her mood.
Her arrows point down when Tamaki is arguing with her because they've got bigger problems: I don't think she doesn't like Tamaki. They point down when Sho disappears, and when she thinks about losing Sho. They point down when she first shows herself to Company 8, but that's probably because she doesn't know if they'll just outright murder her or not. She was probably a little scared.
Her arrows point up the rest of the time, because she's talking about hope and people are listening to her and they want to help save Sho and the world.