The way it works pekische is that if you open just the first Force Data dialog and leave it open, then you can select another unit and that dialog will update with the data for the new selection. In other words, it's just like it was in CO1 when you had only one force data view in the sidebar. So you can click on your units and see the new data for each as you go without the need to open up new dialogs. However, if you want to do a compare between units or to view the other tabs side by side you can. But in this case we need to let the application know that by holding the shift key down and selecting Force Data from the context menu. The Shift key says create an additional dialog.
Note that additional dialogs don't update with the selection. They remain fixe to the original selection. So for example if you want to keep an eye on a particular unit. Select it. If the first Force Data dialog is already open this will update the data in it. But because this dialog will dynamically change you need to then right click and hold the shift key down while you select Force Data from the context menu to open up an additional dialog. Move this one to somewhere convenient. It will stay focussed on the unit. You can then click around on other units and their data will appear in the first dialog but leave the additional one untouched.
I hope I have explained that clearly for you.
