‘I don’t remember any more’ is traumatic and emotional. It’s the other extreme of ‘I’ll never forget’.
In the case of Malala Yousafzai, she was shot by the Taliban for speaking publicly about the right for all girls to go to school. Here, Malala’s memory loss adds tension to the story and emphasises the shocking impact of the event.
Notice that the vivid memory is bland and very normal, again adding to the impact. The slightest of clues hint to the traumatic event that’s about to happen.