NGM YOU COLOR SMART 5.5 plus Guide Rapide page 20

Inserting the memory card: to better manage all the functions of NGM You Color Smart 5.5 Plus, we recommend
you to use a micro-SD card: insert it into the backside of the phone. After powered OFF the phone, remove the
back cover and the battery. Then insert SD card as shown in the figure.
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ENGLISH
WARNING!!
Android 6.0 Marshmellow introduced a new
SD card management. When you first insert it on the
device, you can choose to use your card as internal
storage, instead of external. This option will give you more
storage for your own applications, as you have a wider
internal storage, but in this case you will be asked to
format your SD card, for the exclusive use of your device.
Once your SD card has been formatted as internal
storage, it will be no more readable from any other
device, so you will have to format memory card again from
your PC, to be able to use it for other purposes.