Your boss wants you to protect a workbook, but she also wants to be able to change a few cells after you are done. So, before you password protected the workbook (or a worksheet), you unlocked some cells. Now that your boss is done, you can lock the cells.
Select the cells you want to lock.
On the Home tab, in the Alignment group, choose the small arrow to open the Format Cells dialog box.
On the Protection tab, select the Locked check box, and then click OK.
If you try these steps on a workbook or worksheet you haven't protected, you'll see the cells are already locked. This means that the cells are ready to be locked when you protect the workbook or worksheet.
On the Review tab in the ribbon, in the Changes group, select either Protect Sheet or Protect Workbook, and then reapply protection.
Tip: It's a best practice to unlock any cells that you may want to change before you protect a worksheet or a workbook, but you can also unlock them after you apply protection. To do that, you remove protection by removing the password.
In addition to protecting workbooks and worksheets, you can also protect formulas.