Opening settings on Linux after installation

I just installed Nextcloud on Ubuntu GNOME and connected to my server. According to the System Monitor (or htop) it is running fine and I can also see a Nextcloud folder that is syncing my files in Nautilus. However, I don’t know how to open the settings. Is there some way to open the settings, e.g. through the terminal?

I’ve been using nextcloud for many years now but opening the settings window (from the tray icon) has stopped working a while ago. I have no idea why! There is no error shown in the console from where I started the NC client app.

Maybe it’s because I’m using FVWM2 instead of the more common Gnome or KDE?

I would really like to have this fixed. How can I help the programmers?

Thx, Andy