GNOME Terminal always opens maximised [duplicate]
Solution 1:
Nautilus normally remembers the last Window size. If a window size is near to filling the screen, Gnome Shell (used by Ubuntu 18.04) will automatically maximize. If that is the cause, then turn this of in org.gnome.mutter auto-maximize. With the terminal:
gsettings set org.gnome.mutter auto-maximize false
To undo:
gsettings reset org.gnome.mutter auto-maximize