If you cannot open an Excel file and see Excel cannot open the file because the file format or extension is not valid error, see this post.

When you double-click on a file in Windows, it will automatically open a default program that is configured to manage these types of files. It is common, though, want or need to use a different ...

If OneDrive is very slow to open files in Explorer, temporarily pause file sync, clear OneDrive storage, and reset it. More suggestions here!

Learn how to use a Microsoft 365 setting to choose whether to open files in the online or desktop app, giving you full control for each file.