I have this solved. Just to share it:
With 11g PS3:
Open the human task, in the human task editor, select “assignment”
Click the edit icon for “Task will go from starting to final participant
In the “Configure Assignment” dialog box
Select Assignment tab
Check “Show approval controls in task details only”
These steps will work, after you have followed the steps and redploy, did you check with the existing tasks or with new taks. This will be enabled only to the new tasks and not the existing tasks.
I have followled the same steps, after the redploy the setpp will be applicable to new tasks.