The editor is associated with the file extension on macOS.
When you select one of your code files press Command+I to open the inspector (or choose “Get Info” from either the “File”- or contextual menu) and you will find a section called “Open With:”. When expanded you should see a drop-down menu and a “Change All…” button.
Pick the application you would like to open this file from the drop-down menu and then click on “Change All…”. A dialog will ask you to confirm that your chosen editor shall be used for all files that have the same extension as the current one.
Do this for all file-types where you would like to change the associated editor.