I am curious here, then why did some poster said Yulia had the choice to choose which GP she would go to and she chose TEB and Cup Of China?

so because Russian Fed hosts Rosetele com, their skaters have the advantage to chose GP on their own?
Here's roughly how it works, at least to my understanding (anyone please correct any errors!)
1. First, the host federations make up to 3 picks per discipline from their own country. (Presumably they work with their top skaters, at least to some degree, to do this.)
2. The top 3 skaters from the previous Worlds are the 'seeded' skaters (those retiring/sitting out the GP are removed, so the ladies' seeds this year were Lipnitskaia, Pogorilaya, and Gold). If a host federation chose a seeded skater as a host pick, they sit out this round. If not, then the seeded skater chooses the events they prefer in order of their seeding.
3. A draw is done to determine the order of the next round. In order of the draw, the host federations choose skaters who were placed 4-6 at Worlds. If a host federation chose a 4-6 skater as a host pick, they sit out this round.
4. A draw is done to determine the order of the next round. In order of the draw, the host federations choose skaters who were placed 6-9 at Worlds. If a host federation chose a 6-9 skater as a host pick, they sit out this round.
5. A draw is done to determine the order of the next round. In order of the draw, the host federations choose skaters who were placed 9-12 at Worlds. If a host federation chose a 9-12 skater as a host pick, they sit out this round.
6. In subsequent rounds, the host federations choose from those who are top 24 World Standings and top 24 Season's Best.
So you can see that the top 3 skaters have quite a bit of control and the host federations have quite a bit of control. Probably So-Youn was seen as one of the weaker skaters in the 6-9 round, so federations with strong ladies' programs would have wanted to select her to set up their skaters (eg USFS is trying to get Gracie a soft field, at least to some degree).