changed my AppleID but iCloud did not update it

I changed my AppleID on my iphone6, my MacBookPro and my Imac but I keep getting pop ups on my MacBookPro when I am working that I need to fix my iCloud sign on- I click on it and it takes me to the mac Preferences for iCloud account but the “SIGN ON” still had my old AppleID therefore I am in an eternal loop of being unable to update the iCloud + newly added AppleId...Can’t find any answers in the community.