Let me show you by example in geany. In the image below, you can see I have a file opened called Page.pm. In the titlebar you can see the directory the file is in. Now, if I were to start a new document, the last directory would be the directory Page.pm is in /home/me/Documents/fantasy/files/lib/Base.  Now to get complicated. In the following image, I have two files opened with a new file between them. Page.pm hasn't moved, but main.css is in /home/me/Documents/fantasy/files/css. If I go to the new file from main.css, the directory will be the css directory. If I go to the new file from Page.pm, the directory will be the lib/Base directory.  Now if I were to close all of these files, the last file closed will set the directory. So if I close the css file first then the pm file, the last directory will be the lib/Base directory. When I go to open a file or start a new file, the directory will be lib/Base until I go to another directory for another file.
Does that make sense?