How to stop the manufacturers restricts

Solution
You can't. If the phone is running at least Android 6.0 or newer (older versions can't change to "Internal" from "External" storage) then the only way it works is if the manufacturer didn't restrict the option.

The only other thing I know of requires the device be unlocked and then rooted. Which I would never recommend as you can so easily brick the device.
You can't. If the phone is running at least Android 6.0 or newer (older versions can't change to "Internal" from "External" storage) then the only way it works is if the manufacturer didn't restrict the option.

The only other thing I know of requires the device be unlocked and then rooted. Which I would never recommend as you can so easily brick the device.
 
Solution