File selection menus typically load a default folder depending on what the application programmer sets.
Sometimes, file selection dialogs remember what the user selected the last time they used it and automatically load that same folder. This is often helpful.
Sometimes, though, neither behavior is correct. As a programmer, guessing what the user wants your program to do is tantamount to assuming all users are stupid and you are smart, but this makes you the stupid one. You should always defer decisions to the user when you do not have information to deterministically decide what the most appropriate decision is.
The user should get to choose which behavior is most appropriate each time they use a file selector. The solution is a windowing metaphor in which the user selects between two windows. The windows are mutually exclusive. The user must choose one. The user can swap between the two windows if they change their mind.