How to lock cells in Excel
1. Go to the Review tab.
2. The Lock Cell button is grayed out, which means that the entire sheet has been locked by default.
3. Click the Protect Sheet button, then a dialog will pop up.
4. In the Allow all users of this worksheet to area, Select locked cells and Select unlocked cells these two options have been checked by default. (Note: Other options can be checked as needed.)
5. We enter password in the Password (optional) box, and click the OK button.
6. In the pop-up Confirm Password box, we reenter the password, and click the OK button.
7. Then the entire sheet has been locked. We can not modify the read-only cells on the protected sheet.
(Note: The Lock Cell function can only be used when the Protect Sheet function is turned on.)