On Edit screen you will see the following option, to enable, you need to check all the boxes and then only you can save your settings. Read and understand them carefully..
from the top left drop down you can select “Sign in to another account”, which will take you to following screen. While signing in make sure the email address shown on left is your email address !
Now the next feature would be saving the passwords of the sub signed in account in one, this way it will become single sign on to all accounts. 
You can enable this by login to https://www.google.com/accounts