Many of us use multiple Google accounts (eg. one for school and one for home, which is recommended in school policies) but it's a hassle to log in and out of them all the time. Here is an easy way to set up and switch smoothly between accounts:
1) Log in to Chrome (not just Drive or gMail) using your CESU account (this is automatic on a Chromebook.) Choose "Link Data." This will become the default/primary account.
2) Go to Drive or gMail, click on your user icon (upper right) and choose "Add Account." There is no need to sign out of your primary account before doing this.
Once both accounts are logged in, you can switch smoothly between them by clicking on your user icon in the upper right and choosing the other account.
When you navigate to a service that uses Google login, you will choose the correct account from a list.
CAUTION: Once you enable two accounts, make sure your school work is always done with your school account!