Buttons have a Navigation property that determines the order in which they will be highlighted via keyboard inputs:
Each Button within the scene must have this property set if you want to navigate to all the Buttons. Recall from Chapter 4, The Event System and Programming for UI, we discussed the First Selected property of the Event System component. If you have a Button assigned to First Selected, that Button will be highlighted when you load the scene. If you then navigate throughout the Buttons with the keyboard, the navigation will begin at that Button. However, if you do not have a Button assigned as First Selected, navigation ...
