If you’re worried you may have left your Gmail signed in on a computer you don’t own, potentially giving strangers access to it, you can easily check this and remotely log out from those computers. First log into your Gmail account from wherever you are. Scroll to the bottom of your inbox and look for ‘Last account activity’ in fine print near the lower-right corner of the screen. Click on Details, which should appear just below it. From the window that opens, you will see a list of every device that is currently logged into your Gmail account. There will also be a button that reads Sign out all other Gmail web sessions. Click it and you’ll be remotely logged out.