This forum is for the official (Laminar Research) X-plane software.
The Steam version is not the Laminar Research version. It is a third party version not supported by Laminar Research. Some will argue that it is but it is not. There are comments very early in this forum from Laminar Research that they don't support Steam.
When you launch either the Laminar Research XP10 or XP11 versions there is a check box that it will automatically search for any updates and will load the latest version updates. I can't launch X-Plane at present to check on the latest available official version for XP10. Memory tells me it is 10.51 and there will be no further updates since the release of XP11.
I am not a supporter of Steam so I cannot advise on what happens when the Steam version launches. Perhaps try the Steam Forums.
Hope this helps