I consider the n.b. (no break or no breath) to apply to the preceding notes. I would put the one in the first example after the dotted half note. If you are continuing in the same parallel, the forte would follow the n.b. directly.
Likewise, in the second example, I’d put it after the half note on beat 3. If you split the parallel between beats 3 and 4 and you put the n.b on the new parallel with beat 4, it’s too late – the singer will likely have taken a breath after beat 3. They’ll need to see it directly following the note to which it applies.