Hello,
You need to sed default location for what? Photos, Apps or another?
You can set your camera to save your photos to SD card.
For apps ...If your phone is not rooted you can't do that. You can only transfer your apps to SD card.
Read this ->
http/www.tomsguide.com/faq/id-2908201/move-apps-card-android.html
Regards,
GeRgY