I set our employees into roles by their position. They have different titles but all report to the CEO. Now I realize that only people in the same role can see each others data.

How do I set the roles so that all users can see all data, including all employees seeing the data that the CEO enters? We all talk to the same contacts / companies, so there is no reason to keep anyone's data personal. 

If I change role assignments at this point, will we lose data?