You can set global postback by filling all lines at Global postback`s tab in your account. You should take the right link from your tracker. Then you should choose the transfer method (Post or Get) according to the tracker.
Next press a Save button.
Next at the stream settings you should mark the checkmark «Use global postback» to turn it on at the stream you`ve chose.
Also you can set postback for the stream individually. You should mark off the checkmark «Use global postback» & fill lines for postback`s links, safe the stream next.