更改WPF窗口图标

I have a bunch of icons as resources. Managed to change MainWindow icon without issues, but doing the same thing on others gives me this error:

Could not find a part of the path 'C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\Common7\IDE\resources\add.ico'

我在XAML文件的顶部中具有以下内容:

Icon="resources/add.ico"

So - for some reason it searches for resources in resources folder when in MainWindow.xaml, but in other window it decides to search in VS folder (for unknown reason). How can i fix this?