When content is versionable, the version history is started. The first version of the content is the content that exists at the time of versioning. If you want all content to be versionable at the time of creation, you can modify the definition of that content type in the data dictionary. The definition must include the mandatory aspect versionable.
By default, all versionable content has auto-version set to on. As a result, when content is updated, the version number is updated.
The auto-version capability can be disabled on a content-by-content basis in the user interface. If you want auto-versioning to be off for all content, modify the definition of that content type in the data dictionary.