I have a workbook that is password protected. I have a macro will hide and
unhide columns that users with the password can update. I have a button to
hide/unhide the columns on the sheet that is being displayed.

The problem is the user can unprotect the sheet from the tool bar and then
change the password. How do I prevent the user from doing this?

How can I force the user to reprotect the sheet with the pre-defined
password? Is there a VB event where I can check the new password with the
pre-defined password and force the user to enter the pre-defined password
only? I have password protected my VB code to prevent the users from seeing
the pre-defined password.