Hi Lars, is this question about your iPhone/iPad (an iOS device) or about your Mac (Mac OS device)?

On Mac:

Bookmark Current Tab would normally re-use the last folder where you saved a bookmark. Click the blue star button in the address bar to edit that. There's also a checkbox at the bottom of that panel to have Firefox open it automatically when you add a new bookmark.

If you use a lot of folders, there is an add-on that might be useful for you. The process works the other way around: you right-click (with one button, Ctrl+click) the folder, and then use an item on the context menu to add a bookmark for the current page there. Here's a link if you want to check it out: https://addons.mozilla.org/firefox/addon/bookmark-tab-here/

It's for my new Macbook Air. Thanks! That's exactly the info I need!

Next time if you have a question(s) about Firefox on Mac OS, then please post it in the Firefox section https://support.mozilla.org/en-US/questions/new/desktop/form as Firefox for iOS is for on iPhone/iPad.

/moved thread from Firefox for iOS to Firefox section.