https://gxiangco.gitbooks.io/m3-app-dev/content/part4/%E6%9B%B4%E6%8F%9Bicons%E5%8F%8Asplashscreen.html

1、 change resource icon.png and splash.png

2、ionic resources  

3、check resource android and ios images is changed ?

4、apk
4.1、 ionic platform remove android  then  ionic platform add  android
or
4.2、
ionic build android
copy res android and ios images to platform/android or ios inside