Yubico Forum

Hi! I just bought a Yuikey. I setup my Google to enable Yubikey as the primary 2FA. All worked fine since I was asked to insert the key on the next sign in.
However, after signing out yesterday and then signing back into my Google account this morning on the same computer, it did not require my Yubikey to be installed. In other words, I signed in with password alone.
When I signed in on a different computer, it requested the Yubikey to be inserted.
So my question is whether a computer becomes "trusted" after the first signing in event? Will the computer ever ask me for the key on the future? After signing out, I would have expected that the Yubikey would have been required on each sign-in.
Thanks

If you're using the YubiKey as a Security Key to secure your Google account, and one computer requires you use the YubiKey each time and the other logs straight into your account, that means the computer which isn't asking for the YubiKey was left on the default setting when the Security Key window first appeared (trust this computer for 30 days). You can either clear your browser history on that computer, or you can go into your account settings > 2 step verification, and go to your trusted computers list. You can manually delete the computer from here.

Make sure when you log in again that the option to remember isn't selected.