How can I change the source code for the whole document at once

I am maintaining my educational materials for C# and ASP.NET and in a single document there are 100s of source code section.

How can I change the source code (code block) of the whole document at once.

Also when I copy paste from some website then source code is something else.

There are few more things I wish it should be there in SiYuan

• There should be option to set default (code block) for source code (at application level as well as document level.
• Option to change or replace language of code block from one to another (say from C++ to C#)
• Code block -> Source code formatter (for formatting as we see in IDE and highlighting the keywords or other stuffs). Example as we see in Visual studio to format code with different settings.

Hope someone helps