Re: Adding actors actresses
Do you mean persons tab in left pane ?
This is because left pane shows by default 'in collection' items (movies / persons).
When you add a movie, it is set 'in collection' by default (according to general settings : see using F10 key) so you atomatically see it in movies tab.
As there could be much persons for a movie (actors, directors, and so), only basic infos are created at movie creation time, so these persons are not set 'in collection' and you don't see them by default until you set those you're interested in 'in collection' by, for instance, downloading infos about that people.
Another way to see them without setting all of them 'in collection' (which wouldn't be wise) is to toggle data output from 'in collection' to 'all data' : Quick Filter > Information output > show all data