Hi. With Firefox browser running, I think you need to go to:
Click Firefox preferences.
The peferences window should show the 'main' tab.
Where it says 'downloads' you click the 'save files to' button then 'choose' button and then create a new folder to download to.
Similarly with Safari. Go to:
Safari preferences.
The preferences window should show the 'general' tab.
Where it says 'save downloads to' select 'other' from the dropdown menu and then create a new folder from there.
Needless to say, once you've created a new folder, remember what you've called it and where you've saved it!