Ok, thanks, finally human help! I just had to change my pc and make a fresh install of the operating system. I used Linux mint on the last pc, and have Linux MX 18.3 on the new one, currently in use. I took the precaution of copying my Firefox and Thunderbird folders from the old hard drive, as I have several years worth of bookmarks organised in to folders, irreplaceable. This was the way I had preserved that information in previous changes, and swapping the old folders with those in a new install worked fine. But now i find the new version has changed and the files differ and cannot therefore be swapped. I don't really want to get into blaming or how disappointed and annoyed I am, as this won't be the fault of the person helping, and that is appreciated. But back ups need to be backwards compatible or there is no point? So, not sure which version I had, but will have been a couple of years old with updates. In my 'etc' folder there was a Firefox folder, and in that I have a folder marked pref. In that folder there is a file named apturl.js and I have saved those folders. With my new install there is not even a folder for 'firefox' in my 'etc' folder. How do I proceed to restore my bookmarks? If I need to install and older Firefox version I will do so. Many thanks, Tony