You can store multiple versions of your document in your Kahootz workspace. Version control allows you to see all previous versions of the document that you have uploaded or made amendments to. You can explicitly add a new version of a document, or upload the same document again and it will be added as a new version of the existing one. You can view the document version history and download specific versions.
Each saved version can be given a helpful label that describes it and makes it easier to spot key versions in the list. E.g. 'First round of post-review edits'.