Here is another solution which I feel is more sensible for those working on Android Studio:
- Expand the project root folder in the Project View
- Right Click on the app folder
- In the Context Menu go to New->Image Asset
- In the pop up that appears select the the new logo you would like to have(image/clip art/text).
- If you were selecting the image radio button (as is the default choice), if you clicked on the 3-buttons to show the path tree to locate your .png image file, most probably you might not be seeing it, so drag it from the Windows Explorer (if Windows) and drop it in the tree, and it will appear and ready for being selected.
That is it! You have a new logo for you app now.