When I boot my laptop using my live-usb, and then change the settings (e.g. desktop wallpaper) and then reboot, the settings go back to default. How do I make the live-usb save the settings?
With a typical persistent install changes are stored in a file named casper-rw.
Maximum size of this file is 4GB due to the limits of the FAT file system.
You can also have persistent ext2, 3 or 4, partitions named casper-rw and home-rw, of any size that will fit the drive.
Casper-rw stores your downloaded programs and home-rw stores your settings, email and downloads, etc, (but is optional).
Once the casper-rw file or partition exists, the session can be made persistent by pressing F6 on boot and then typing persistent.
This can be automated by editing syslinux.cfg or text.cfg and adding the word persistent.
I prefer to overwrite the contents of syslinux.cfg with the following:
default persistent label persistent say Booting an Ubuntu Persistent session... kernel /casper/vmlinuz append file=/cdrom/preseed/ubuntu.seed boot=casper persistent initrd=/casper/initrd.lz quiet splash noprompt --
This has the advantage of removing the Try/Install screens and reduces boot time by 30%.