How to tell Visual Studio to use a different source code directory to debug into a library?

I provided clients with a C++ class library that they use in one of their C++ project. They want me to investigate when a specific assert happens in the library, and sent me their client code to debug it. I reproduced the assert on my computer, and was prompted by Visual Studio to specify a directory containing the source code to the library, for debugging. I selected my development directory, but noticed that when navigating the call stack in Visual Studio, it directed me to wrong places in the source code. I realized this was because the directory I notified contained newer source code for the library (not the source code that was used to build the library that was sent to the client). Fortunately, I have the source code that was used to build the library that was sent to the client. Unfortunately, I do not know how to tell Visual Studio to use this source code directory instead of the one I erroneously specified before. How can I change it?