To upload one APK for each arch, you need to create these APKs with different version codes. (android:versionCode
inside your manifest).
The store will deliver to the user the compatible APK with the higher version code, and there is no downgrade. So you need to respect this rule: x86 APK version number > ARMv7 APK version number > ARMv5 APK version number > version numbers you were using before having multiple APKs.
The store will understand the APK is for a specific arch if you have the associated libs/ARCH folder inside your APK.
When you upload your APKs to the store, you first need to switch to advanced mode:
then you can upload all the APKs you want, with different ARCH support and different version codes. Once its done you'll see a summary with the version codes and differences between the APKs that are uploaded, and you will not be able to go back to simple mode: