You can change the app icon to your favorite one from "Design" → "App Icon" in the settings screen.
In rare cases, an app icon change may not be applied correctly.
If this happens, turn off your device completely, restart it, and then try changing the app icon again.
This should resolve the issue.
This is an iOS issue, and restarting the device usually resolves it.
If the icon still doesn't change after restarting your device, please contact us via the "Contact Us" button at the top right of the app's help screen.
Thank you.