Didn't occur to me that the order of bookmarks ends up being quite random. It's probably a good idea to sort entries in :bmarks
menu.
I've tried editing the vifminfo file but it doesn't work.
While this isn't recommended to change that file manually, you can reorder bookmarks there. It's not recommended partially because vifm might affect your changes like in this case. Before editing this file close all instances of vifm you have running, otherwise quitting them later will undo your edits.