My apple and itunes id are synched but my icloud is an old apple id and I can't figure out how to delete it and change to current Apple Id. i tried to delete it but I have to have the oassword and the knes I know of are not working. Thanks for any he

I have an iPad 2 with most recent update 8.1.3. I have been experiencing connection problems, wifi dropping all the time. I get the prompts to enter passwords for iCloud and i Tunes all the time. I finally synched my Apple ID with my iTunes ID but the iCloud is still connected to an old email. I cannot figure out how to delete it as iCloud is not accepting the password I am using. I go round and round with changing passwords, etc. What am I doing wrong? How can I sync everything?