What is she going to do?

Perhaps she is confident as a group (in this case, a choir) but when she is alone, she is timid and her voice sounds weak. Maybe she needs to pretend nobody is there or something.. like she's singing in the shower. It makes one more comfortable when they imagine nobody is there and especially with American Idol auditions, you want to sing like nobody's watching; I find I do my best when I pretend nobody is there or when I'm alone/ That's when I have the most confidence. :) I would recommend an oldie's song and a new song. By the sounds of her voice, she should be able to sing Break away with extreme ease.