I've got one.. havent used it but looking at the instructions I see theres a flow chart which lays things out pretty well... if your unfamiliar with how a pid and the different settings work I suggest doing a search over at you tube.. if pid or inkbird pid doesnt pring up a lot , try mypin .. the modes and parameters are pretty much all the same and it will give you an idea of what you want to do and why.
autotune only has to be redone if your changing a parameter such as volume or flow by a lot.
auto mode is pid mode.. You dont really want this for the boil. you want manual mode but with this model pid (Which is different than any other ove heard of) It seems you want to set the temp higher than 212 in manual mode and then set your duty cycle which is the power level for the boil.