Both. I just used Explorer as an example I was thinking of File Explorer but ideally I'd like to be able to fix this for any program / Windows feature, including Firefox.
Thanks for the link to the tutorial, that's about something a little different to what I'm looking for, though it does look useful in its own right. I probably didn't explain what I want very clearly. It's not the target folder that's the problem for me, it's the window size and location on the screen.
Here's a more detailed explanation of what happens that I'd like to change:
I open (for example) File Explorer and position and size it to what I want.
I close that.
Next time I open it, it has the same position and size.
That's fine, but:
If in the meantime I happen to open File Explorer and change its size or position, then the original size and position is lost and replaced by the new one when I close it.
And that's the problem. I want to know how to fix the size and position so that it stays that way whatever I do with instances of File Explorer in the meantime.
[It probably looks like a strange request. The reason I want it that way is because I'm having to use a "mouse recorder" utility to automate a process (which records and then plays back mouse clicks etc.), and in order for that to work, the window must open in a reproducible position on the screen every time, otherwise on playback the mouse will fail to click in the required place relative to the program. An alternative solution would be to instead use a DOS batch script (or something similar) that wasn't dependent on mouse and screen positions at all, but I don't know enough about programming to do that, hence the mouse recording method]