We have a computer at work that our service techs get on in the AM. We have a dispatch board that shows what and where they need to go that day. Some of the techs see this and they change who goes out there. This is a shared file on Excel so me and 3 of my co-workers here in the office can make changes and it will update. How can we lock this out since it is on our network. I have already made it a read only on that computer but they figured out how to get around it.