What is the correct way to navigate between pages in a WPF application?

Question

WPF

(1 question) How are the transitions between pages implemented correctly? I use frames, but every time I have to turn off other elements, otherwise they hang on top of everything.
(question 2) There are 3 windows and a combo box. The first window, a combobox is attached to it via xaml and the user selects a value in it, it is transferred to the next page, but the combobox remains at the top (I did that the frame is not full page). Then there is a choice with a bunch of buttons, the user selects one and throws it on the third page. But if you select the same thing in the combobox, then the user is not redirected to the second page, but he also remains on page 3, what is the reason?

Answer 1

Use MVVM and Prism