How to change code block language to C#

How to change code block language to C# as default for whole document or current document when

• source code is pasted from some source
• normal text along with source code is pasted (mixed mode)
• copied from markdown file (.md) either from SiYuan or from some other source

In my case when I copy paste the content from .md file, the source code language is automatically changed to something else. instead of remaining same (C# in .md file)

When exported in .docx format, the source code color is being lost

If someone could suggest, I am thankful and grateful to them