Yes, it is very clear now. True, "conditional branching" is displayed differently in the Preview mode and in the Answering questions mode. I agree it might be useful in some cases to have the same kind of display in both modes, but that is not possible at the moment. It would need a lot of development.
Joseph
Sorry, I do not understand your question. Please re-phrase it.
I do not understand "But for students this text box, only appears when they click on next page."
Joseph
Have you tried the combination of settings described here?
https://docs.moodle.org/27/en/Adding/editing_a_questionnaire#ALL_Responses_viewing
J'y comprends de moins en moins. De quoi parle-t-on exactement ?
"[...] les commentaires sur le fichier d'annotations de PDF d'un devoir"
C'est quoi, ça ? Tu veux parler du plugin https://moodle.org/plugins/pluginversions.php?plugin=assignsubmission_pdf ?
Joseph