How to change the threshold value in orange? How can I change the threshold value for each classifier? In the ROC analysis curve we are allowed to remove the tick from "default threshold"
I don't think you can do it for classifiers or any other widgets (for example confusion matrix). 

For classifiers, workaround would be exporting the data along with the precise classification values (via "Predictions" and "Save data" widgets) and using external tool to process them.