You can easily change the memes that appear in your Quizizz games in the Quiz Settings page.
You’ll see the option to pick your memeset just below with the Show Memes setting.
(The Quiz Settings page shows up right after you click the “Play Live” or “Homework” buttons on the quiz page.)
You will be able to pick from any of your completed meme sets, or any of the featured meme sets. Just click the thumbnail to select the meme set of your choice.