Why are Notes and iMessage not syncing to iMac, and why is the Apple ID icon not updating?

I have an ongoing, frustrating question about Notes and Messages not sharing to my iMac (Venture 13.7.4). Additionally, upon editing my Apple ID icon: I chose a photo, only to be sent back to the generic Lime green background. I have restarted, logged out of Apple Id, shutdown, restarted, restarted. Enough ! What further do I need to REREGISTER MY APPLE ID ?