Choosing the correct android version is important when picking money making phones, because some apps will not work on older android phones. Check your phone Specs online, or if you are buying a new one check the packaging for the android version. I have found that most money making apps work on kitkat (android 4.4) or higher. Below is an android version list to help you when buying a farm phone, or checking phones you already have. You don't need the latest version to run a lot of these money making apps, but it doesn't hurt.
Android 1.6. Donut.
Android 2.1. Eclair.
Android 2.2. Froyo.
Android 2.3. Gingerbread.
Android 3.0. Honeycomb.
Android 4.0. Ice Cream Sandwich.
Android 4.1. Jelly Bean.
Android 4.4. KitKat.
Android 5.0 Lollipop
Android 6.0 Marshmallow (API 23)
Android 6.0 Marshmallow
Android 7.0 Nougat
If you have any questions, leave a comment, and as always "fear not its only money".