I bought a used iPod and I can’t connect to anything. The previous owner’s profiles are still in the iPod. How do I change it over to my username and password for apps like Facebook and YouTube? It says it can not connect.
Plug the iPod into your computer, open up iTunes (or download/install it if you don't already have it), click the iPod at the left and click Restore. This will completely delete everything on the device and restore it to factory settings. Then just sign in with your own Apple account and download the apps you want.
Whoever sold this to you is irresponsible, giving you access to all of their accounts.
Why can't you connect it to anything? The simplest way to reset all of the settings is using iTunes: you can restore the device to factory settings. This is important because you're probably using someone else's iTunes account right now. Other than that, you could try deleting and re-installing the apps.
iOS: Understanding 'Erase All Content and Settings' -
It sounds like you want to reset it back to factory condition, in which case, this link will provide the essential information:
Whenever you buy a secondhand item, always reset all the settings so that you can customize it personally. If the problem presists, contact Appte for right directions.