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

If you see The file couldn't open in protected view error while opening Microsoft Excel, the fixes listed in this post will help you.

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

It is possible to create a macro in an Excel sheet that unlock the sheet which is already protected by a password. Users can easily prepare a document in the sheet and then lock it again with a ...