There are many different reasons users might want to change the default upload directory in WordPress. It makes it possible to host images on a subdomain for performance reasons, which can also make backups more efficient. People also sometimes change this directory in order to create a different URL structure and organization for their media files.
Before WordPress 3.5 you used to be able to change the upload directory path from the Settings menu in the dashboard. Unfortunately, it’s not that easy anymore, but it’s still possible.
How to change the default media upload directory
Open up your wp-config.php file, located at the root of your WordPress installation, and add the following code:
The codex specifies that it should be added before the line that says require_once(ABSPATH.’wp-settings.php’);.
If the directory that you are defining does not yet exist, WordPress will automatically create it as long as wp-content is writeable. Otherwise you can just go in and create the directory yourself via FTP. Make sure to make the new directory writeable.
Change upload organization
You can also change the way WordPress uploads are organized. Navigate to Settings > Media in the dashboard and you’ll find the option to check or uncheck the box next to “Organize my uploads into month- and year-based folders”.
Changing your file organization so all your media files go into one folder will help to make your URLs simpler. It also makes it easier to see all of your files in one place via FTP instead of having to rifle through multiple month and year directories.