I installed many tools for changing shortcuts.

Among them, 'AutoKey'  is the best for my work circumstance. 

sudo apt install autokey-gtk

AutoKey's graphic interface helps a user be able to maintain many scripts.

In my case, I need to change Copy and  Paste shortcuts to Alt+C and Alt+V.

Here is the example script.

keyboard.send_keys('<ctrl>+c')

Using this script, you can change your copy shortcut except for 'Guake' application which is a good terminal app.

And then, you can set Alt+c on Guake's shortcut to your own preference - if you do not set Window Filter, Guake recognizes Alt+c as ^C, and in rare cases, it might lead to disaster.