Mac Sierra says "installed" but version 10.9.5 showing
I am trying to upgrade MacBook Air (2013). When I go to the App store to download Mac Sierra, the download button is not available, as it reads 'Installed'. However, when I go to 'About This Mac' it shows I am running version 10.9.5. I have restarted my laptop a few times. I am trying to upgrade to run other apps that require a more current version of iOS. Any help you can provide is greatly appreciated!
MacBook Air