I see from your profile that you are blind, so you're likely missing some context here. The "Opening Quotes" are more aptly described as title cards that appear

I see from your profile that you are blind, so you're likely missing some context here. The "Opening Quotes" are more aptly described as title cards that appear at the end of each opening. Generally, the title cards are the Futurama logo with short gag-lines, although it's not entirely text as there are often visual elements as well. The images are video screengrabs of each title card, rather than something the author created.