When I open a PDF file for the first time, I can alter it and save it multiple times. But once I close it and then reopen it to change it, I cannot then save it again. I get the message "The document could not be saved. The file may be read-only, or another user may have it open." I can then save only with a new name. The file properties: the read-only box is not checked. Under the Edit tab, under Properties, under Documents, and under PDF/A View Mode, I have chosen the option "Never". I am not on a network and am the only user (single computer). Can I throw a switch somewhere so that I can save the document under the existing name?