I accidentally checked (or did not uncheck) the "Do not ask for 2FA on this PC again" field when I logged into Gmail on a PC that isn't mine.
Is there any way to reset this setting? I looked around in settings without finding anything.
From Google Help:
Removing trusted computers from your list
You can remove computers from your set of trusted computers at any time. To do so, sign in to your account and go to your 2-Step Verification settings page. Under the “Advanced” section, you’ll have the choice to remove the computer you’re using at the time or all other computers. If you choose to remove other computers from your trusted list, those computers will automatically sign out of your account, and you’ll be prompted for a verification code next time you try to sign in from them.
That text is somewhat out of date from the UI. On the Verification Settings page, click the "Registered computers" tab, then "Other registered computers" - "Change setting", then "Require codes" to sign out from all other computers (besides the current one). They'll need the password and 2FA to sign in again.