You've structured your platform so that Surveys are a subset of Quizzes, and because of this, Surveys have all the trappings of the Quiz tool. And there's *no way to customize wording*. They're not the same thing. They're very different approaches to engagement.
Quizzes.Next doesn't actually do surveys at all—more importantly than the language used to convey what kind of content it is, it doesn't even support the content you're looking for. There's no way to create multiple-choice questions without a correct answer, for instance, like there was in Classic Quizzes. The only workaround anyone seems to have found so far is using only open-ended questions, which are way less convenient. I'm rather frustrated about it as well, as I'm trying to help some instructors migrate their content and the surveys are stuck in Classic Quizzes for the foreseeable future. I'm hoping this gets added to the list of things Instructure finishes before Classic Quizzes are deprecated.