How to change the default "Ctrl-RMB" search hotkey?
The "Ctrl-RMB" is already used for my translation software Babylon.
I can't find any setting about this by myself.
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.
RMB = Right Mouse Button
It can't be changed, because it's hardcoded.