As GUWonder said, the upgrade remark in your endorsement box most probably has nothing to do with status/miles upgrades. There are certain fare rules to every ticket you buy, including for example changes. If you have a W-fare you can change but there is no availability on the new date you want, then your fare may allow you to upgrade it to a V-fare, paying only the difference. This fare however, does not seem to allow you to do that.