You can make Excel always open old spreadsheets in Protected View. Enable or disable Protected View using in-built setting, Group Policy, Registry.

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.

A CSV (comma-separated values) file is a text file in which information is separated by commas. CSV files are most commonly encountered in spreadsheets and databases. You can use a CSV file to ...