Navigation bar change after update

goto Appearance – Menus – Manage locations – select the navigation menu.

if for example you want to set cat as a sub munu to animal,then it should look like this.

Animal
cat
pop art
School
teachers
class room

here is a link to how it should look like
https://www.joinmost.com/wp-content/uploads/2015/12/Capture-Menu.png