Choose best model by auROC instead of auPR

[cuauty]

I am new comer of TransmogrifAI and working on running Titanic Binary Classification according to the link. Currently I try to choose the best model by auROC. I revise the example's code as follows.
val evaluator = Evaluators.BinaryClassification.auROC().setLabelCol(survived). setPredictionCol(prediction)
but don't achieve it. The model is still chosen by auPR.

Could someone help tell me how to do it? Thanks a lot.