With the Excel file open select File in the top-left corner of the screen, followed by Info. Select Protect Workbook, then choose Encrypt with Password.

Working with an Excel workbook that contains confidential information such as financial data, personal details, or trade secrets? Here's how you can protect the data in your Excel file from prying ...

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.

When a worksheet is hidden using `xlSheetVeryHidden`, it cannot be made visible again through the Excel user interface, adding an additional layer of protection to your sensitive data.

Protecting a worksheet in Excel 2003 prevents others users from editing it. For example, if you have tracked and charted your business's sales on a sheet, you will want co-workers to access the ...

Crisis averted–kind of. Permission to copy the entire workbook is another problem. For instance, if you open a protected Excel file in the browser edition, you can see hidden formulas.

I'm going to hazard a guess that it was being saved in compatibility mode in the original excel format. Somebody "updated" it, and the password protect would have died with it. You'll either need ...