This is a small update, but an important one for a lot of shop owners. Two new settings are available for configuring the ‘Notify me’ button. You can choose button to appear on the left or right, and the image used for the button itself can be selected.
You can use any image that has been uploaded to your store as part of the theme (note that this is different to product images). Once you’ve uploaded your image, return to Back in Stock app and choose your custom image. You may need to clear your browser cache (or restart your browser altogether) to see the new image.