This article explains how to set up your browser to change how frequently you are asked to sign into your account.

You can change the length of time you remain signed in to Yahoo! by following these steps:

1. Sign into your account.
2. Click on your name in bold at the top right hand corner of the screen and select the Account Info option. You will then be prompted to enter your password again for security purposes.
3. Go to the Sign-In and Security section and select Change Sign-in Settings to change the frequency.
4. The options for Sign me out every are Day and 2 Weeks.
5. Click the Save button to update your account's sign-in settings

If you wish to remain signed in permanently, place a check mark into the Keep me signed in box on the Sign-in page.