Many of us have multiple Google accounts for a variety of reasons. You can use Gmail and Google Calendar for your work too much, but you prefer to save files to your Google Drive personal account.
Google has added features that make it easy for you to sign in to multiple accounts at once, so you do not have to log out of a Gmail account to check someone else's emails.
You can simply use the address accounts.google.com / AddSession to log in to your personal Google account from the same program while you are already logged in to your work account.
Η connection is easy, but switching accounts is difficult
Once you've already logged in, click on your profile image at the top right and select any Google account from the drop-down menu to switch to that account.
The default account is the one that appears at the top of this list and is the one you first signed in with. So if you type mail.google.com into your browser's address bar, you will automatically be taken to this account. To set another Google account as the default, you'll need to sign out of all your existing accounts and sign in with this account first.
This obviously is too much work for users who need to be logged in and unplugged continuously between multiple accounts.
Below we will see a simple trick with URLs that will help you quickly change Google accounts.
Open the Gmail account of your interest and press Ctrl + D (or Cmd + D on Mac) to add a bookmark.
Once you have added the new bookmark, right-click on it and select Edit to modify the bookmark. 
You need to add the item "autuser=email@gmail.com" after the last symbol (/) and change the name of the shortcut to the name of the email you are using as shown below and save.
Repeat steps for all your other Gmail accounts.
With just one click, you can quickly get started with the Gmail account you are interested in, even if this account might not be your default Google account.
The trick works with all services του Google Apps, όπως το Google Drive, Contacts and Calendar.
https://calendar.google.com/?authuser=giorgos@iguru.gr
https://drive.google.com/?authuser=giorgos@iguru.gr
https://contacts.google.com/?authuser=giorgos@iguru.gr
