edit file.gnucash

[Harold]

I was wanting to edit the gnucash data file that I have in Mint Debian to make sure that it didn't have the year 1969 that causes a problem in Windows XP. I tried to open myfile.gnucash in version 2.4.7 with gedit and firefox. Gedit gave me an error and couldn't open it. Firefox didn't open it but allowed me to save it which I didn't want to do. Then I tried opening it with the archive manager. Extracting gave me an error. Gedit gave me the same error from inside the archive manager that it did earlier.

What do I need to do to open my data file?

Thanks,
Harold