Thanks for the prompt reply, nice to get help so quickly. I followed the first part and the backup tool was a bonus. However I didn't quite follow the second part. When you say:
connect your android with dropbox in Joplin on a path similar to this: configuration -> synchronization -> synchronisation target -> Dropbox…
Are you talking about a new notebook on the android? What I am trying to do is sync an existing PC notebook with my phone app. I tried the steps above in 'configuration' on the phone and after saving nothing happened? Is there something I need to add that connects the phone app to the file in Dropbox?
Thanks for your patience. As I say above the frustrating thing is I got it to work on my previous phone but now seem to have lost the steps to make it work.