How to change page title on page-update and make it show in panel

i am basically repeating my question here after having used the wrong thread:

i am changing the page title everytime the user updates a page in the update()-call of my model:

public function update(array $input = null, string $language = null, bool $validate = false): ArtistPage {

        $input['title'] = $input['artist_name'] . ' ' . $input['artist_firstname'];

        return parent::update($input, $language, $validate);

This works, but the panel only reflects the title-change after i reload the panel.
How do i make the title in the panel update without calling “changeTitle”?
What is the difference between “update” and “changeTitle” call?

I am using virtual pages in a mysql database following the examples provided (overwriting “writeContent”-Method) but that should not have anything to do with this, should it?