Dose it matter doing hifz from which copy of quran ?I memorize some of the surah and 30 th juz during childhood.Since it was I was revising from same quran ,My mother gave that quran to masjid since some of the pages torn out.Now started revising from other quran copy I don't why at some of the point I couldn't recollect.I guess it because of placement of surah on pages are different.I told this my mother ,she said it has nothing to do with my memorization.Since I can understand arabic only 20-30% and my way of memorization was on page basis.