ajay
5
There is more than one way to skin a cat (in Joplin, as it stands now). Have you considered keeping your topics separate in ...
a) different notebooks (as Laurant suggested), or
b) different profiles the way it is provided within Joplin (e.g. on a desktop explore this option by going to menu->files->switch profiles
c) different profiles completely separated (manual setup), the switching is a little more "labor", but you have more control over the results
d) running more than one instance of Joplin (on Mac, Linux, probably possible too on a PC).
One of these options should please you, no ?