I just tested with Acrobat 11, and although it allowed me to select Tools > Pages > Header& Footer > Update and enter new values, it did not allow any changes and gave the following error message when I tried: "You do not have sufficient permissions to perform this task"
Are seeing something different and are any changes you make to a secured document allowed, and if so, and are you allowed to save the modified document?
George, you're awesome! And now I feel like an idiot. I'm not sure why I didn't walk through the whole process to see if it actually let me commit those changes. And, as you discovered, even though the buttons are there, it doesn't actually let you do it. I tried both a header and a Bates Number. Neither worked. The secretary just confirmed the same thing.
Thank you so much, sir!
This could be considered a UI bug and is at least confusing, so you've brought up a valid issue. I can't think of a reason that a user should be allowed to make the attempt when the changes aren't possible. You are prevented from making other types of changes when security settings don't allow them, so the same should probably apply here. Consider submitting a bug report if you're so inclined.
Good call. I think I will do that.