Understand the idea
Saved sessions and autofill make a shared device convenient for the next person as well as for you. Logging out is an essential final step.
Put it into practice
Avoid saving passwords on shared profiles, sign out through the website and close the browser session. Remove downloaded records containing private information.
Know the limits
Closing a tab does not necessarily terminate the signed-in account session.
The wider context
Stable devices make online reading and practice easier, but performance settings cannot change the odds of a game. Back up important data before disruptive troubleshooting. Use manufacturer documentation for model-specific steps and keep software within supported, trusted distribution channels.
Your next step
Use the practical step above only where it fits your situation. Before an account-specific action, check the current instructions from the service or device provider involved. Write down what you observed and what remains uncertain; that makes a follow-up question more useful.