Whenever saving images or files from websites, you have noticed that Firefox seems to save the files in seemingly random folders, or it won't remember the last folder you saved an image to. You're not the only one, and it's really annoying.
Luckily there is a simple fix for this problem and it involves adding a setting into the about:config section. Firefox will remember the last download directory on a per domain basis & will offer you that as the default choice when you download from that site again. When saving files from multiple domains, it would appear that it forgot the last download location.
In the address bar, simply type in about:config. This will show a warning screen, then allow you to access a load of hidden features inside Firefox.
Once you have confirmed the message, right-click anywhere on that page and create a new boolean preference named
browser.download.lastDir.savePerSite and its value set to false.
Now Firefox will remember the last folder files were saved to for all domains, and the annoyance will stop.