After drawing a dark rectangle over some text in order to block out some sensitive data, it looks like it disappeared on the screen. Although then saving the file and re-opening the file, the blocked out text is not visible BUT the blocked out text is still selectable and can be copied and pasted. A user would expect that if a blank box is drawn over something (such as text) that something (such as text) would no longer be there.
I have found no other way to remove or cover up sensitive data.
See uploaded file 'Adobe-Example_edit-save.pdf' there is a black rectangle over the word 'General' in '1. General Terms' which all looks ok but if you highlight the text, copy and paste it somewhere the word "General' is still there. This is the problem and is very deceptive.