If you want to change the category of a client, if you want to assign a different representative or apply a different tag to a group clients, you do not have to do this one-by-one. It suffices if you search for a group of clients that you are interested in, i.e. all the clients with an ‘Offer’ status. Next, you will mark the checkbox at the top of the list next to the Client name, and from the menu bar that will appear you can select the option which you want to attribute to the whole group, i.e. ‘Sales department’. The system will automatically assign the Sales department to the whole group of clients. 
You can do the same for every other option which is available from the option bar at the top of the client list.