How to set default download location to external we card on Samsung tab 4 10.1

Solution
Unfortunately, you can't. At least not on the OS your tablet came with. The only OS that currently allows for turning a SD card "Internal" rather than the standard "External" is "Marshmallow". If you can upgrade to that, you 'might' be able to make it work. However your device would need to be capable of doing so (upgrading the OS and making the change to the card).

Should it allow those changes, then you just need to make sure the SD card is blank before proceeding, as the change over will format the card and also encode it to that device. Making the card unreadable if placed in other devices.

If your tablet won't allow for the upgrade or even after getting it, it won't let you change to "Internal", then the only thing I know that...
Unfortunately, you can't. At least not on the OS your tablet came with. The only OS that currently allows for turning a SD card "Internal" rather than the standard "External" is "Marshmallow". If you can upgrade to that, you 'might' be able to make it work. However your device would need to be capable of doing so (upgrading the OS and making the change to the card).

Should it allow those changes, then you just need to make sure the SD card is blank before proceeding, as the change over will format the card and also encode it to that device. Making the card unreadable if placed in other devices.

If your tablet won't allow for the upgrade or even after getting it, it won't let you change to "Internal", then the only thing I know that would work is rooting, which I could not assist you with.
 
Solution