Set your browser to enable cookies
Cookies are small bits of information stored on your computer to allow for quicker access to things. If you're unable to stay signed in to a Yahoo webite, check that your browser is set to accept cookies. If it’s not, you may have problems getting and staying signed in.
Edge and Safari enable cookies by default - If you've blocked cookies, you'll need to unblock them. Check with your browser's help documentation for step on how to do this.