Wrong Browser Opens

macOS defaults to Safari for web links, even if you installed Chrome or Firefox.

Change Default Browser

System Settings > Desktop & Dock > Default web browser → pick your browser.

Change Default Mail App

Mail app > Settings > General > Default email reader → pick your app.

Change Default App for a File Type

1. Right-click any file of that type → Get Info
2. Under "Open with:" → select your preferred app
3. Click "Change All..." to apply to all files of this type