How do I fix this error- Some of the purchased items on this iPhone could not be transferred to your library because you are not authorized on this computer-when I am authorized?
I have an old Mac book pro with all my music, this has music from cd's and other sources from the past 15 years which I really need and dont want to purchase again!, I have bought a new MacBook now and I can not sync my iPhone with music or it wipes out all my old music and only allows iTunes purchases with the error code, so I can only sync with my old MacBook, I found some information on this problem for windows users to try help but nothing for apple device issues?
MacBook Pro 13″, macOS 10.13