I don’t want to see “Choose” in my combobox when I start form. I need to see specific value. How?
It depends whether it is to be, for example, the first value from the list or the default value. If you want the first value of the dictionary to be always displayed, all you have to do is uncheck displaying Choose (checkbox “Wyświetlanie ‘Wybierz…’” in combobox properties):
However, if you want to display a specific value then its dictionary key should be entered in the default value property (“Wartość domyślna” in the section “Jakość danych”):