I stand to be corrected. My response was outdated and coming from the traditional OWB
In OWB none of the task level ETC is editable.
When the same project is opened in CA PPM (13.3)
at first all task level appear to be editable
However, after saving
all of the ETC's were not saved. Adding a number after the task name for identification
So it is tasks 5 and 9 where the ETC was not saved. Looking at the assignments
Those two tasks have no resources assigned.
So the conclusion from this point test is:
The functionality regarding editability of task level ETC in CA PPM is different from OWB (and maybe from earlier Clarity versions) : Task ETC can be edited if there is/are resource(s) assigned to the task otherwise not.