You can save the file with a password, with a read-only option. Doing this means that others can open the WB, they can even make changes - but they will NOT be able to save the file at all, so it will always remain how you last saved it

To do this, click file/save as, select Tools/General Options, and select Password to Modify
Note, you MUST remember your password, there is no way to recover it if you loose it