I don't know how to set the default storage settings on my phone. I go to my storage settings, but it doesn't give me an option to do anything other than to mount, unmount, and delete data on the SD card.
As stated below, if any of the steps here are missing on your device, then either the device is using the wrong version of Android, or the manufacturer has restricted this option.
First, you need to be using a phone that is running at least Android "Marshmallow" (or newer) or be able to upgrade to it. Second, you will need the instructions I am including below. And third, you need a phone that has not been restricted by the manufacturer from making this change. Which does happen.
NOTE: If any of the steps are missing on your phone, or they don't work for you, then you have a phone that either has an older Android version or has been restricted by the manufacturer. If that is the case, you will not be able to use this information.
How to turn the "External" SD card into "Internal" storage on "Marshmallow" a.k.a. 6.0.
NOTE: Please be sure you start with a blank SD card. It needs to be blank because when the card is converted to "Internal" storage, it will be formatted (wiped) and encoded (making the cards data only readable by that device).
1. Go to device “Settings”, then select “Storage”.
2. Select your "SD Card", then tap the “three-dot menu“ (top-right), now select “Settings” from in there.
3. Now select “Format as internal”, and then “Erase & Format”.
4. Your SD Card will now be formatted as internal storage.
5. Reboot your phone.
NOTE: If you don't reboot the phone, many things may not work correctly, so make sure you do.
How to turn the "External" SD card into "Internal" storage on "Nougat" a.k.a. 7.0.
IMPORTANT NOTE: Be sure you start with a blank SD card. When the card is converted to "Internal" storage, it will be formatted (wiped) and encoded (making the cards data only readable by that device), so anything on it prior would be gone.
1. Go to "Settings", and then select "Storage & USB".
2. At the bottom of the list you should see the SD card's details, including the option to format it and make it "Internal" storage.
3. Once this is done, reboot the device and you can start running things from the card.
If you don't reboot the phone, some things may not work correctly, so make sure you do the reboot.
OK "Webworkings"...that is NOT what "CanaanMcBee'" even asked about!! Clearly you do not have a ZTE phone to use as reference! CanaanMcBee: I'm not sure which ZTE you have, mine is 783 7VL. On MY phone, I go to APPS>Storage and the very first thing is says on that screen is "Save Location". When I touch that, it brings up a mini-window that allows me to choose Phone or SD card. HOWEVER...I have no idea WHAT it saves on my SD, but I've downloaded apps and they STILL go to my internal storage. I think it may save some data to the SD, because I can see that the MB's have increased (minimally). If you have this option, please let me know if it works for you...I'm really beginning to HATE this phone!
It depends on what it is you want to download to the card. If you want to be able to download apps directly to the card, the above instructions are needed to get the card to be "Internal" storage. This is for apps only, and only works on some devices, others are blocked by their manufacturers. For just standard files (not apps) no changes to the SD card are actually required. Those would be done through individual apps, to change where they save their files. Say the browser for example.