project .net framework version and compile/publish

I have the project compile set to use 4.7.1, however I put code in  to show .net framework, Response.Write("Version: " + System.Environment.Version.ToString()), and when running program in debugger it shows "Version: 4.0.30319.42000" why the discrepency?

I need the program to be running at least 4.6.2 for some TLS features I need

also I published project to my local IIS, when I run the program there, evidently the response.write code is not in that published version, because the output doesn't show on the page as it does in the page rendered by the debugger?

also the file system program dates in the published IIS directory don't make sense at all.  the program modified date is older than the create date? and neither date reflects the most recent compile date for the publish date.

what is going on here?