In the "Lest We Forget..." section you find some additional forms and information.
Redeem Voucher[]
Voucher codes can serve various purposes, but the only kind that users frequently see are the "invite codes" used for duels with friends. The invite codes follow the "quizcover:" header. They can be entered in that form, though it's most convenient to just tap on those links.
Some vouchers enable you to bring up a particular question, but if you do so, the points won't count for rankings, streaks, achievements, records, or whatever.
Licenses[]
Quizcover uses various third-party modules, and in this section you can view their license terms.
Credits[]
Go there if you're curious who worked hard (some of them for about three years) to bring you Quizcover.
Feedback[]
There is a question-related feedback form that you can access via the Post-Solution Screen, but for general feedback, such as ideas for new questions, you can use the form that is accessible via the "Lest We Forget..." section of Settings & More.
Quizcover Wiki[]
Quizcover links to this wiki (also from its home screen), though its makers give you a warning that they don't control the content on this side, so they merely recommend it, but don't provide any guarantees for it.