Using Classic Outlook on Windows for personal email, calendar, and contact management
What browser are you using?
Does it happen in other browsers? Try all three (FireFox, Chrome, Edge). I tested the Office 365 Excel ribbon size in Firefox and MS Edge, and the Excel ribbon was the correct size. I found this is a browser issue, not a Microsoft issue. On Google Chrome, the Office 365 Excel ribbon was just too big.
If it is Chrome, try this.
Once I isolated the Office 365 Excel ribbon size issue to the Chrome Browser, the fix was Super Easy.
- Open an Excel Office 365 document in Chrome.
- Go to setting the three-dot menu on the upper right.
- Change Zoom to 100%.