@raphaelmartines I went to that screen and it only showed recent sign in activity. I have done the various suggestions above. My sync is still showing that I'm signed into 7 devices (at least 1 is an old work laptop that I even uninstalled opera from before returning it), when I should only be syncing with 3. Deleting a logged account session doesn't log you out from there.
I still have yet to come across something that makes sure I have been logged out of other computers. I'm not sure if just changing my password will do the trick.