You can change or set up new buttons for input very easily in UE4.
- Click on the button "Edit" (in the top over the Viewport)
- Then click on the point "Project Settings"
- Then a new window should open. On the right should be list of different Things to configure for navigation
- Under the Headline "Engine" is a point labeled "Input" click on it
Here is the current layout of buttons (v1.0) to control everything I set up
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