If the background color of the illustration is similar to the background color of the canvas, it will be difficult to distinguish between the illustration background and the canvas background.
When this happens, you can make your work easier by changing the background color of the canvas to a different color to clearly distinguish between the illustration background and the canvas background.
*This feature is a prime feature
Tap the ①Back button and select ②Settings.
Tap the ①Background Color and ②Change Background Color.
After you changed the settings, select ①✓.
Then you are finished.