Changing path for media upload folder in wordpress multisite

This has been answered Hook filter to change wp_upload_dir() path in multisite , including code to hook into the upload_dir hook.

Note that there is a setting in wp-config.php for the ‘base’ upload folder

define(‘UPLOADS’, ‘wp-content/myimages’);

So with this code, the uploads folder is wp-content/myimages.

But, that changes the place WP looks for the media, so you will have to move existing media files to the new location, if you use that setting to change the ‘base’ upload folder.