Sorry if this question is silly, or if it has already been answered. If I get a new computer and want to put odrive in the new computer, do I have to sync or unsync all my files and pics from my old computer?
Your installations on separate systems are independent, and you can install on as many systems as you like. This means you can just install odrive on the new system, login, and then sync what you like. Your old computer can stay exactly as it is.
Just keep in mind that changes you make to the cloud on either system will be reflected on the other. So, if you update or delete a file on one computer you will see that reflected on the other.