If the disk is not partitioned, how come you have only 32Gb free?
Anyway, the option you claim for registration, is actually only for the Trash size! It exists, of course, also under OBH and you have it entering the movie list, highlighting the Trash (Deleted items) and pressing MENU. Then, if you choose "Settings" you'll see the option but its meaning is clearly explained in the description of the option.
You can't decide the recording assigned space, then: only the trash size limit, fortunately.
So, if you have only 32Gb free isn't, perhaps, just because you misunderstood this option and you set it to a too big limit? Doing that, you subtracted space to the recordings, indeed.