I wasn't able to install Linux as a bootable operating system from my USB sticks (8 GB, PNY USB 2.0), so I put the live version on instead. I was wondering, if now after having installed some things if I can add persistence to the operating system and save changes as if it were installed correctly in the first place?
Try this link, it explains how to make a persistent USB Linux install using a free tool:
Here is a solution to make an existing USB install of Ubuntu have a persistient storage location
please note I have not tested this method, so if you have anything on your USB drive you absolutley cannot loose please make a full, tested backup of your thumbdrive before attempting.