If I use AI Document Scanner on an assessment where questions have already been answered, will this impact those questions?

No. AI Document Scanner generates responses only for questions that are still unanswered. It skips any question that has already been answered by any means, whether entered manually, answered by a previous scan, or answered by an earlier auto-response, and does not overwrite existing answers.

Because of this, subsequent uploads only affect unanswered questions. For example, if you upload 10 files and the scanner answers a set of questions, any later upload is used only to answer the questions that remain unanswered. (As a reminder, the 50-file limit is cumulative across the assessment, so later uploads draw from the same total.)