- Open CSV files in Excel, instead of Chapters
- Open CSV files in Excel, instead of Numbers
- Right-click on an Excel File (.xlsx, .xls, .csv, etc)
- Click on Get Info in the pop-up.
- Click Open With if the section isn't already expanded.
- Click the dropdown and choose Microsoft Excel
- Click Change All...
- Click Continue when the Finder asks you if you're sure.
Now any time you open a file with that extension, the Finder will automatically open it with the app you've selected.