If my players have skill points, I can click on auto-assign or put it into a skill they are learning. My question is where will the skill points go to if I click on auto-assign? It always asks if I'm sure about doing it and I always do that.

Another question, is only training the way to level up the quality of players or are there any other ways? Because I have players that are only 3 stars in my team but I want them to have 4 or 5 stars.