How do I change the default save folder?

This addon does exactly what I want to save the images on the website by hover the mouse over the images.
But there are some unuse features which could be removed for slim down the codes, unmainternance codes?

Good job! Does exactly what I need it to do, thanks! ... Question. I can't seem to select the greyed out box for 'File renaming' section. Why is this? ... Also, will this addon be valid and working in the next Firefox, ie, 'not legacy'... Looking foreword to your response. :)

Edit: Thanks for your quick response! ... Actually, there is no 'legacy' warning on this addon, sorry. I was just getting paranoid that some addons might not be properly marked as legacy when in fact they might end up being... I don't want to start relying on addons only to have to delete them later when Firefox forces me to. So I'm keeping it! :)

Too bad about the file renaming/folder saving issue, however, Firefox will save to whatever you set it to, (Even if you set Firefox to always ask!) and auto increment is working, so it's workable... Really surprised at the lack of availability of these types of addons for Firefox as this is an extremely useful tool.