How can I change the root path that an application uses to upload a file from?

[user033088]

I have an application which is used for calibration for electrical components. Here I want to set a rootpath for this application. I did some research and I found out that I can get the rootpath of the application (that is where the exe is stored) But what I am really looking for is once I start the application the root path should be what I assign. For instance currently the root path is "C:\Users\Public\Documents\ABC.Tools\Projects" but I would like the root path to be "E:\New ABC\"
Is this possible? I wrote some code where I call the exe of the application and it opens the file in a folder that I specify :

private void NewJournal_Click(object sender, EventArgs e)
{
 
string filePath = @"E:\New ABC\abc.vnalog"
if (!File.Exists(filePath))
{
return;
}
 
string SelectedFile = @"/select, " + filePath;
System.Diagnostics.Process.Start(@"E:\New ABC\abc.vnalog", SelectedFile);
 
}
 

Now this code open the .vnalog file in the application. And this works great..!!! How can I now change the path within the application?
Thanks in advance for your help.

[weaknessforcats]

This path in Windows:

"E:\New ABC\abc.vnalog"

is this path in C/C++

"E:\\New ABC\\abc.vnalog"

since the \ is an escape sequence.