In my Ubuntu 18.04.2 Machine i have GNOME shell 3.28 by default. I installed GNOME shell 3.30 snap package using command:
snap install --edge gnome-3-30-1804
But my GNOME version isn't changed to 3.30 it is still 3.28. What to do now? How can I switch versions?
In short, no, you cannot run a newer Gnome Shell version through snap.
The snap you install contains core library files. It is intended to run the latest Gnome apps such as Fotos, Maps, System Monitor, Calculator on an older Gnome Shell using snap technology. In fact, in Ubuntu, System Monitor and Calculator by default come as a snap app.