Hello, Ben Nguyen2
Welcome to Microsoft Community.
I realize that you've encountered a problem with Excel on Mac. Texts in all cells seem upside down in your spreadsheet. I understand how you feel.
Please check your Office version and make sure it’s the latest. It may be a compatibility issue related to version.
Open Excel> in the top menu, click Help > Check for updates > update Excel.
For more information, see Update Office for Mac automatically - Microsoft Support.
If it doesn’t work, we may require more detailed information from you.
- Excelversion: Open Excel> click Excelin the upper-left corner, > click About Excel. You can see the version number and share us with the screenshot.
- Do other programs in the Office suite, such as Word/PowerPoint/Outlook, etc., also have the same problem?
- If you open the same files in Excel online, does the problem still exist?
- If you create an Excel document by yourself, does the problem still exist?
Once we receive your response, we may recommend more troubleshooting steps.
I'm looking forward to your reply.
Best wishes,
Lucia Wu - MSFT | Microsoft Community Support Specialist