The UUIDs may look rather differently depending on the partition type. Most examples assume ext4 partitions.
First make sure the mount point "/media/DATA LARGE" exists. With the partition unmounted (if necessary, right click→unmount), check for the existence of the directory "/media/DATA LARGE". If it's not there create it: sudo mkdir "/media/LARGE DATA". Any other name will do too, but I think you already instructed firefox and thunderbird to look there. The line to add to /etc/fstab is
The \040 is there to escape the space character in the name of your mountpoint. There can be some discussion about the right options you want. Maybe someone else has a better idea. Most of them are actually the defaults.
UUID=4133-3f3d /media/DATA\040LARGE vfat rw,noexec,nouser,auto,async 0 0