Changed Apple ID successfully but won't let me change on iCloud

Hi all

I'm so confused, can someone help please? I successfully changed my Apple ID on my Mac and this is confirmed and is now verified. I've followed the instructions on how to change details on my phone and ipad and have done what it said (followed instructions in this linkHow do I change my apple ID e mail address on my phone), but when I go to iCloud in 'Settings' and click on 'delete account' it asks for my password associated with the previous email address. I have put this in but it is not recognised and just keeps asking me to put it in again.

It's the same with my iPad. I have a lot of photo's and stuff stored in iCloud and I can't access this on any of the devices. Help!

Thanks