Copy and Paste on a posted journal entry


I have noticed I can't just copy a field and paste it into another window while in sage. Is there some way to do this?  For example i am looking at a journal I posted yesterday. I am writing a new journal and want to use the same reference. So I go to the journal I had I click the cell for the reference (because I already posted I can't open that cell to edit it) and it highlights the cell. But I can't just hit ctrl + c and then go to the reference on a new journal entry and hit ctrl +v.