After using Linux Mint with Cinnamon for a long time I am now back with Ubuntu with GNOME (reluctantly, I may add).
One thing I have noticed is there does not seem to be an option in the settings to change your preferred terminal emulator.
Luckily it can be changed in several other ways,
The generic fix
in a terminal, write
In this case I have changed to the Tilix terminal emulator.
The Debian/Ubuntu fix
Done using update-alternatives but the above should be more generic (as in, I have no idea how it’s done on other platforms)
If you do this, org.gnome.desktop.default-applications.terminal should be set to x-terminal-emulator.