To remember all password is bit difficult.But in MAC,there is an utility called Keychain Access.This utility will store all passwords that are used in MAC.
Click on Finder.
Go to Application > Utilities > Double Click on Keychain Access Icon.
Click the Lock Symbol ,a new window will pop up,type your administrator password here.
Click the password catagory and in the left pane,double on the required application.
After you double click,you can see a window.Check Show Password.
Enter your password and click allow.
Lock the Key.