UI canvas covered in Scenes. after click, UI is invisible.so hard to edit in Scenes!

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Hi guys! I write a game login page. When i click game paly, everything goes well. But when i click the previous UI elements in Herarchy and i find that they are invisible in Scenes. They are all covered by my “ExitPopup”. It is so hard to edit in Scenes. Is there any suggestions? thanks!
I thought it might be the layer problems? or canvas‘ structure?
Here is the screen shot: