I don't know what "RMB" means, but to change the default hotkeys in C::B you need the keybinder-plugin.
It's part of the contrib-plugins and is distributed with C::B.
If it is installed you can go to "Settings -> Editor -> Keyboard shortcuts" to change the key binding.
You did not tell us anything about your C::B version or your OS, so I can not tell you how to fetch the plugin, if it is not yet installed.