dropdown selection save only after page refresh

Hello!
I’m beginner with a wordpress. I’ve been trying to make custom theme.
Theme should have featured area for 3 featured pages.
I used pages, and added them through widget on my homepages.
For selecting pages i used wp_dropdown_pages() to get all pages as dropdown.

My problem is that, widget don’t change to selected option after selecting it from dropdown and clicking save. But after page refresh it’s changed.