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

Find out how you can disable Protected View & remove Read-only in Microsoft Office programs like Excel, Word, PowerPoint, etc, via the Trust Center.

How to enable Protected View in Excel 365 First, launch Microsoft Excel 365 and then select the Options button from the Home screen.

Protected and unprotected cells look the same in a spreadsheet. To delete all unprotected cells, you must select all of them at once, which can be easily done by using the Find and Replace feature.

Using Microsoft Excel 2007, you can protect worksheets in order to keep other users from making changes. Unfortunately, this protection applies to everything on the worksheet, including groups.