If you bought some devices from US or Europe, which runs on App that are only available in their respective IOS App Store or Android Playstore, you can follow the following steps and install the respective apps on your handset.
The following is using US Apps as example:
Apple IOS App Store – How to Install iPhone Apps Not Available in Your Country
How to Get US Playstore On Any Android (Android Tips)
Hope the above helps
Cavarii Online Store 