I bought a new 7GB MicroSD card to use as an internal storage for my Galaxy J7 for media, and use the phone's internal storage for apps only. Although, everytime I download something (picture, song, screenshot...etc) it's saved on my device's original storage, so I have to manually move everything to the SD card. Is there anything I can do to set the SD card as my download's default location? [strike][/strike]
First, you are using the card as "External" storage, which is what it is intended for. For it to be "Internal" storage would mean to convert it over to run apps from it, which would also encode the SD card and make it unusable by any other device (or even that device were it to be reset).
Second, it is very simple to set up the files to download to the SD card rather than the "Internal" storage. You just have to change the "Settings" within the app you are downloading through. So say you are using a browser, you would go into the browser app, and then into that "Settings" and change the download to location. If the app does not allow for this change in its "Settings" then you may need to install and use an app that does.