To change the background image of a note, tap Note Settings button at the bottom of a note.
In the Note Settings, tap "BG" to see thumbnails of background images. Swipe right or left to see more (You can also use arrows to move thumbnails back and forth).
Tap a thumbnail to change the background image. Tap "Done" button to close Note Settings.
When you choose a background image, font color and type will be changed to match the image. If you like to set font of your choice, after changing font, tap "Save" and " Overwrite the default BG". Your saved font settings are paired with the paper background image.