How to show my Buttons over texture ?

Hi, i am new user of unity, and make 2D game. I created buttons, and they appear properly when i play the game in unity, but when i build the game, they dont appear(there is only track and car). When i change in Canvas RenderMode: Screen-space-Camera, they appeared , but they are "under" texture(track). How to make buttons to be "above" track, or to be proprely appeared in canvas renderMode :ScreenSpace Overlay?