Visual Studio allows you to choose the C# language versions for your project. To achieve this, In Visual Studio, from the Solution Explorer, right-click on the project and select Properties -> Build Tab, and then Select Advanced button. This will bring “Advanced Build Settings” windows, where you can check the drop-down option for “Language Version”. You can refer to one of my old tip – How To Check Default Language Version In Visual Studio?
In the Earlier versions of Visual Studio, the language version used to set as default, to pick the default languages version installed. Now, there is a change. By default, it now referring the to major released version – (C# latest major version) starting from the release of language version C# 7.1. With that selected, you will only able to use the features of C# 7.0, irrespective of you have other versions like C# 7.1 or C# 7.2 installed. Unless you made explicit changes to select the minor version it will use the major version as default. Navigate to Properties -> Build -> Advanced, select “C# latest minor version(latest)” to pick latest installed minor version.
C# latest major version is the default language version set, and choosing the “C# latest minor version” it will always refer to latest C# version, in this case it will refer to C# 7.2.
Here is the quick difference between two version of Visual Studio
Hope this helps!