Ctrl+Alt+t is the keyboard shortcut to open a terminal in Ubuntu. By default, it opens an ‘x-terminal-emulator’ terminal.
I wanted to change that to use my favorite terminal emulator, which is ‘terminator’
To do that:
gsettings set org.gnome.desktop.default-applications.terminal exec 'terminator'
or:
sudo update-alternatives --config x-terminal-emulator
That’s it!
Enjoy!
Source:
https://askubuntu.com/questions/70540/how-can-i-set-default-terminal-used-in-unity