Accessing the different accounts of Apple, how do I manage this confusion?

I have recently change my password for icloud or Apple or Itunes? I have several passwords now than I can handle of which is for which services. Do I have a website I can go to as for this information? Otherwise, the difficulty of getting the right password or email ID becomes very difficult struggle as I want to access Itunes from Pandora to purchas some music and or puruse through Apple's newest products etc.; or icloud services which always seems to deny all the passwords I have accumulated from the constant changing of new passwords that affect the other services accessibility.

Having to manage this is very very frustrating. Your immediate attention will be appreciated.

Aloha and thank you; Sincerely

Richrad Kuaana Jr ~ Kelikeke