How can I manage bookmarks in Android Firefox?
Here's what i did. Assuming you've set up the sync process:


Go to Firefox on your PC, click Bookmarks in the top right corner
Choose Unsorted Bookmarks. This opened a new window for me where i could see a section called Mobile bookmarks that i hadn't seen anywhere else.
Click and drag this Mobile Bookmarks folder to either Bookmarks Toolbar or Bookmarks Menu, whichever you want it to appear under (Note: the Bookmarks Menu is what we clicked on to start this process, i advise you try both and see which you like best).
Profit.


Hope this helps!