Andrew T Liebeknecht wrote:
I'm have an iMac 21.5 Mid 2011, (running MacOS Sierra 10.12.6) and can't synch my iTunes to my iPhone 8 Plus (running OS 15.4.1) and my iPod touch (running OS 15.4.1). Why can't my iMac recognize them?
You tell us. What happens when you plug the iPhone and the iPod in? Where are you looking for them? Do they not show up in iTunes? See instructions here: Link-> Use iTunes to sync your iPhone, iPad, or iPod with your computer - Apple Support
I also have a MacBook from around the same time period, not sure what OS I'm running on it. Shouldn't I be able to see all my songs, even those I've put in my computer from CDs?
Not unless you manually copied the songs to the MacBook. They won't just appear on another Mac as if by magic. You need to actually take steps to get them there.
The only other option would be if you are subscribed to Apple Music or iTunes Match and have used the iCloud Music Library feature. Then the matched or uploaded songs from the computers would appear on other devices that have the Sync Music library switch turned on. click here-> Turn on Sync Library with Apple Music - Apple Support
