Following the instructions at tutorials.ubuntu.com I created a bootable USB stick running Ubuntu 16.04.4. It boots and runs Ubuntu fine but I can't save any files. I made a few test files and saved them to Documents. But the next time I booted from the stick the files were not there. It was like the first time the stick had been used. Also the network settings such as Wifi network and password were not saved. Is there a way save files and setting changes to a USB stick? Or do I have to be using regular HD? Thnaks
The basic (and standard) USB drive with Ubuntu is a live-only drive. The files that you create will be stored in RAM, but will disappear at shutdown and reboot.
There are two alternatives, a persistent live system with a casper-rw file or partition or an installed system (installed like installed into an internal drive). It is possible to install application programs, to tweak the system and to save files in a way that survives shutdown and reboot in such systems (in USB drives).