Many browsers are designed to remember the email and password of the signed in user. If you are using Seesaw on shared computers with Google Sign in, you probably want to disable that feature.
Here's how to disable Username/Password fill in Chrome: https://support.google.com/chrome/answer/95606?hl=en. Read the "Choose to Save Passwords" section.
Here's how to disable Username/Password fill in Firefox:
https://support.mozilla.org/en-US/kb/control-whether-firefox-automatically-fills-forms. Read the "Prevent Firefox from Storing Form Entries" section.