I think, I have done as instructed by Joplin years ago, when I took it into use. Anyway now I deselected the Jopling folder mentioned above and tested with a new note. I did get synchonised to my phone and an edit I made there got back. Now if the notifications stay away, I’ve reached my goal. Thanks!
“Local sync client” etc. are Hebrew for laymen, so I hope that there is a “Joplin for dummies” documentation that explains terms.