Is there a way to set TAB button to work as 4 spaces in Visual Studio 2010 instead of going to Edit->Advanced->Untabify Selected Lines?
For VS2010 and above (VS2010 needs a plugin). If you have checked/set the options of the tab size in Visual Studio but it still won't work. Then check if you have a .editorconfig file in your project! This will override the Visual Studio settings. Edit the tab-size in that file.
This can happen if you install an Angular application in your project with the Angular-Cli.
See MSDN blog