Juggling Google Accounts
The reason for this is that Chrome is not meant to be logged into more than one Google account. Chrome works best when you have one Chrome window handling your Prep account and a separate Chrome window handling a personal account. Here's what I mean:
The first step to set this up is to log your whole Chrome browser into one account. To log into your Chrome browser, look for the button in the top right of the window next to the minimize/maximize buttons.
Make sure you select the option to "link data" if you are asked. This will carry over browser preferences that you've set, such as bookmarks. Logging into your Google account through the Chrome browser will auto-populate your bookmarks on a new computer.
Creating a desktop shortcut
Adding a second account
From here, you repeat the above steps to add a second shortcut. When you're done, you will have separate Chrome icons on your desktop. When you need to check personal mail, simply select your Personal Chrome icon -- when you need to check work mail, go back to your desktop and select your Work Chrome icon. You can have them both open at the same, in separate windows.
This is valuable during presentation day in class. So, if you have one student after another that needs to log into their Google Drive to get their presentation, just open an incognito window and they can log in without you having to log yourself out. It also doesn't save their profile info, so when the window is closed they are logged out for good.