How to lock a cell

1. Select a cell or a range of cells that you wish to lock.
   
2. Go to Review and click the Lock Cells icon .
   
3. In the Lock Cells dialog box, switch the Lock toggle from its default Unlock option for the collaborators you wish to restrict.
   
4. Alternatively, you can right-click on the selected range and click Lock Cells.
   

The Lock icon will turn green near the specific collaborator once you lock those cells.The locked cells will remain locked for any new collaborators added to the spreadsheet.

 

How to lock a sheet  

1. Click Review and select the Lock Sheet icon
2. In the Lock Sheet dialog box, switch the Lock toggle from its default Unlock option for the collaborators you wish to restrict.
   
3. You can also lock the sheet by right-clicking the required sheet tab and using the context menu.
   

Locking cells and sheets is available only to owners and co-owners of a particular spreadsheet. If you have "Read Only, Read/ Write" or "Read/Comment" permissions, then you cannot use Lock Cells.

How to unlock locked cells

1. Click Review > Manage Lock settings .
   
2. The dialog box shows all the cell ranges and sheets that have been locked by the user for various collaborators.
   

A green lock icon indicates that the particular cell range has been locked for that specific collaborator. Click on it to unlock the locked cell ranges for that collaborator.