Why is my memorization not firm, even though I have memorized the Quran, and I don't know the location of the verse or surah when asked? What is the reason for this, and is it due to sins or varying abilities?

To perfect and solidify the memorization of the Quran, one must consistently review and maintain it, present it to proficient memorizers, and study it with those who have a stronger recall. Furthermore, sincerity to Allah, supplication, performing acts of obedience, and avoiding sins are among the greatest aids, for sins act as a barrier between a person and beneficial knowledge. Teaching and helping others memorize the Quran are considered among the strongest means to solidify what has been memorized, in addition to understanding its meanings, interpreting its verses, contemplating them, and acting upon them.