Cannot Change Target Framework?

Question

A modern class library should use multiple target frameworks today, which means the options can only be set in project files right now,

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFrameworks>netstandard1.4;net40;net45</TargetFrameworks>
  </PropertyGroup>

https://learn.microsoft.com/en-us/dotnet/standard/frameworks

Visual Studio does not yet have suitable UI elements to reflect the options, and that’s why it is showed the way you saw.