When you set the due date on a schedule this date is put on all the tests. This article will show how to update the individual tests.
The schedule due date is set to all the test on that schedule at the top.
When you are on the tests window we can see the due dates on the right hand end.
If we select an of the tests and right click we can select the due date in the list. There are some predefined times and calendar.
Using this we can select more than one test and select the due date. With the search at the bottom and the group by on the list you can select any combination of test.