I have a 128GB partitioned SSD with Ubuntu 18.04 and Windows 10 installed, and I want both systems to use the internal 1TB HDD (which has one NTFS partition) for data such as the Downloads, Pictures, Videos and Music folders which should be common between the two OSs.

In order to achieve this, I set up the HDD to be automatically mounted on boot at /mnt/sda1 (using gnome-disks), moved the stuff already in the folders on Ubuntu to the HDD and created symbolic links in /home for those folders (by using ln -s /mnt/sda1/Downloads ~/Downloads etc).

Everything seems to work fine, except all the files I moved are now owned by root and have permissions set to 777. I didn't do this manually so I assume it's a consequence of moving them to the mounted drive, hence my question: how can I change ownership and permissions for these files? I tried using both chown -R and chmod -R but neither worked (nor did they give an error message).