Objective Protect Excel Workbook, Worksheets, and protect cells in Excel to help maintain the integrity of the spreadsheet and reduce errors. This Protect Excel Workbook tutorial is suitable for users of Excel 2010/2013/2016/2019 and Microsoft 365. Would like to have these 3 sheets password protected but not have the dialog box pop open each time you open the excel file to type in a password for each use. How to Protect Cells in Excel Workbooks 5 Easy Ways. Excel workbook has 6 sheets 3 are for admin people only to see.