save pdf write protected document with highlighted text

I do have a problem. In some pdf files I can not save the pdf dokument of my reference after I have highlighted it. It says to rename the dokument. This is possible. But it doesn´t show the renamed dokument after closing it and trying to open it again. Can anyone help me?

Hi Fluegel, Only the original PDF is attached to your reference, if you have to save it with a new name, you will have to attach that PDF.

But shouldn’t one be able to save the revised document to the same name retaining the modifications?  I thought this was possible, but I also had trouble in a test after reading this thread.