Editing The Default Download Location

After installing Endless OS along with the Windows 10, I kept 2 separate drives with 1 more drive containing both the OS. But while booting Endless OS, a new drive is present with the least storage space containing the sysroot which is the destination for the app being downloaded from the flatpak. I want to edit and create a different destination folder for my downloaded apps in the separated drives so that I can download apps of larger file size.