OP - you choose one side and stick to it until Pantheon resets.
Yes it may suck if you're stuck on the losing side, but also think about it this way -> if there will be a way for people to change sides, then what will hold people on losing side from switching to winning and gettting all the benefits? The distribution of players will be unequal and that would cause a whole lot of other problems. So just play it out, get more skills, learn and next Pantheon choose wisely 
