Follow the next steps in order to change the standard folder for uploaded images:
- Download and install FTP client (FTP Clients).
- Open FTP client and enter your FTP access credentials (host, username, and password) to access files on your server.
- Navigate to "yourwordpresswebsite" directory.
- Open your "wp-config.php" file, located at the root of your WordPress, and add the following snippet:
where "wp-content/uploads" is a path to the folder with the images. Change it to the one you need.
- Make sure you add this code before the line:
require_once(ABSPATH . 'wp-settings.php');
If you want the previously uploaded images to be accessible, please move the content of "wp-content/uploads", which is located in the root WordPress directory, to the folder you specify in "wp-config.php".
Note for a version older than 4.3.6: Gallery plugin works only with the attached images. I.e. the images are added to the gallery only if they are uploaded to your server. They cannot be selected from any external source.