You could say that the changes that you mention can be viewed as maintainance. As such, there are to be expected and could not need approval. However, it depends of the shop (or IT department ). Logically, such maintainance requieres a log and a audit trail. Something that involves more than 50% of modification of a certain asset, however, can be viewed as "change". Upgrade one program in a image is a maintainance, but upgrading a image to the last version of a OS is a change, under this idea.