one approach is to shrug about the size of Canon RAW files and get a modern computer.

* Find the file type(s) that you want to change the application to open with
* Get Info about a file that is of that file type, say a .mov
* Click the ‘Open With’ arrow to expand an application list
* Choose the application you want all files of this type to open with (in this example we’ll use VLC to open all .mov files)
* Click “Change All” and then “Continue” when the confirmation dialog appears