If a worksheet contains cells you do not want changed, you can lock them so that they cannot be edited or deleted. You can also add a password to a sheet or workbook to protect the entire sheet or workbook.
If you have columns and rows that you do not want anyone to see or change, you can hide the columns and rows and then display them again whenever you wish.
To set cell protection, perform the steps in the To Do exercise. You want to lock all the cells in your worksheet except for the numbers for March in column D.
In the Summary sheet, select cells D4:D8. You want to protect these cells from being locked.
Choose Format, Cells. The Format Cells dialog box appears.
Click the Protection ...