The Choose Character screen is used to pick from the list of Characters, those appearing in the shot. Click on the desired Character and then on the ‘<’ button to move the Character from the "All Characters" list to the "Appearing Characters" list. You can also double-click on the Characters name or if you want to add all the Characters use the "<<" button.

Removing Characters works the same way, by double-clicking or using the ">" and ">> " buttons.

Click the "New Character " button to add characters to the "All Characters" list.