How to Set Excel as Default Program on a Mac

NOTE: Before step 1, please ensure you're right-clicking the file while it's in view in the Finder, not your list of Downloads in your web browser.

1) Right-click on an Excel File (.xlsx, .xls, .csv, etc.) in Finder 

2) Click on Get Info in the pop-up menu

3) Find Open With and expand that section if it isn't already open

4) Click the dropdown and select Microsoft Excel

5) Click Change All...

6) Finder will open a pop-up to ask if you are sure - click on Continue

BONUS: This same process works for defaulting any type of program (Ex. PDF instead of MacViewer, Microsoft Word instead of Pages, Microsoft PPT instead of Keynote, etc.)