Once you move past "single class or multiclass", you cannot move back to the race and gender selection. The pop-up only exits forward.
That means, if you want to look at customization for more than one given race/gender, you have to redo the entire introduction walk of shame.
This is ... poorly planned. Are you going to be fixing it?
Could we either be able to back up past the single/multi pop-up window or else have a save point at the Pallid Knight's card table?
I'd like to have a look at the game, but I'd like to explore some options first.